Carbazole derivatives, such as MeO-2PACz and 2PACz are known to improve the performance of halide perovskite solar cells by facilitating hole transfer. To assess their interaction with halide perovskites, we probed the hole transfer from excited CsPbBr3 quantum dots to MeO-2PACz and 2PACz using emission spectroscopic and transient absorption techniques. The different oxidation potentials of these two carbazoles result in divergent interactions with CsPbBr3 QDs. Whereas MeO-2PACz quenches the emission of CsPbBr3 QDs, 2PACz enhances the emission by remediating the surface traps. Transient absorption studies confirm the formation of MeO-2PACz+• cation radical with characteristic absorption in the near IR region. No such oxidation process was observed with 2PACz. The mechanistic insights into the interaction of the two carbazole derivatives with excited perovskite nanocrystals will add another piece to the untold story behind the improved performance of perovskite photovoltaic devices.

Abstract Photoinduced phase segregation remains a major roadblock to the long-term stability of photovoltaic devices employing mixed-halide perovskite absorbers. To address this issue, we use carbazole derivatives, often referred to as “self-assembled monolayers” (SAMs) with phosphonic acid as anchoring groups, typically used as hole transport materials at the buried interface, as surface treatments. Beyond their affinity for metal oxides, the phosphonic acid anchoring groups in these SAMs bind strongly to undercoordinated Pb2+ ions. 2PACz and MeO-2PACz exhibit distinct functionalities due to the energy alignment between the perovskite valence band maximum and the carbazole HOMO levels. While 2PACz passivates surface defects as evidenced by the increase in PL emission, only MeO-2PACz suppresses phase segregation and I2 expulsion via combined effects of defect passivation and hole extraction. By incorporating “SAMs” between the mixed-halide perovskite film and the spiro-OMeTAD hole transport layer, we fabricated photovoltaic devices with improved open-circuit voltage and stability under continuous illumination in open-circuit conditions.

Iodine electrochemistry plays a critical role in driving iodide-oxidation induced halide migration in 3D halide perovskites. When subjected to light illumination or electrochemical bias, mixed halide perovskites undergo halide segregation followed by iodine expulsion from the crystal lattices. To mitigate such intrinsic halide ion mobility in 3D perovskites, lower-dimensional (2D) perovskites are employed as barriers to stabilize the perovskite layers. Interestingly, 2D halide perovskites also exhibit halide ion mobility that is dependent on the binding configuration, viz., Ruddlesden-Popper (RP) and Dion-Jacobson (DJ) phases. Hybrid RP-DJ perovskites with a mixed Br:I ratio of 50:50 show increased stability following continuous photoirradiation. Spectroscopic studies that probe iodine migration and expulsion in photoirradiated 2D films of different configurations are presented here. The effective strategy of blending two different 2D phases (RP-DJ) offers new opportunities to develop stable 2D/3D perovskite interfaces in solar cells.

InfoMetricsFiguresRef. ACS Energy LettersVol 10/Issue 3Article This publication is free to access through this site. Learn More CiteCitationCitation and abstractCitation and referencesMore citation options ShareShare onFacebookXWeChatLinkedInRedditEmailBlueskyJump toExpandCollapse EditorialMarch 14, 2025Correlation, Causation and ComparisonClick to copy article linkArticle link copied!Prashant V. Kamat*Prashant V. KamatUniversity of Notre Dame, Notre Dame, Indiana 46556, United States*Email: [email protected]More by Prashant V. Kamathttps://orcid.org/0000-0002-2465-6819Open PDFACS Energy LettersCite this: ACS Energy Lett. 2025, 10, 3, 1540–1541Click to copy citationCitation copied!https://pubs.acs.org/doi/10.1021/acsenergylett.5c00631https://doi.org/10.1021/acsenergylett.5c00631Published March 14, 2025 Publication History Received 26 February 2025Accepted 27 February 2025Published online 14 March 2025Published in issue 14 March 2025editorialCopyright © 2025 American Chemical Society. This publication is available under these Terms of Use. Request reuse permissionsThis publication is licensed for personal use by The American Chemical Society. ACS PublicationsCopyright © 2025 American Chemical SocietySubjectswhat are subjects Article subjects are automatically applied from the ACS Subject Taxonomy and describe the scientific concepts and themes of the article. Charge transfer Kinetic parameters Order Power conversion efficiency Quantum mechanics Effective data presentation remains a key feature of scientific publications. Data compiled through instrumental analysis or computational outputs need to be carefully analyzed and presented in a way that a reader can understand the gist of the data. Well-composed graphics and schemes, thus become the heart of scientific publications. Since the modern-day automated instrumentation allows collection of large number of data sets in very short time, many authors find it convenient to upload such results or outputs without taking additional efforts to carry out quantitative analysis. Often multiple panels are crammed into a single figure making it difficult to visualize individual data sets. It is not uncommon to see 12–20 panels presented in a single figure without a coherent message or detailed discussion of individual data sets in the main text. Such a presentation of crowded data panels without discussion or an analysis fails to make a positive impact. If the results presented in a figure cannot be read or understood, it is unlikely to impress any reviewer or reader.In our previous editorials (1−3) we have discussed important elements to make effective presentation of data in figures. Three categories of data presentation, viz., Correlation, Causation and Comparison are briefly discussed in this editorial to draw the attention of authors to compose their data in an effective way.CorrelationClick to copy section linkSection link copied!When the values of Y- and X-axis are associated via a linear or nonlinear trend, the relationship between the two variables are considered to be correlated. The data presentation made with a Y-axis parameter in such a case predicts correlation with the X-axis values. Figure 1 shows the association between measured rate constants of electron transfer and the calculated free energy (ΔG) values. (4) The theoretical fit based on the Marcus electron transfer theory is used to show the expected trend of rate constant dependence on ΔG. In order to show the relationship between the two variables, it is a common practice to plot the data scatter and predict the trend with a theoretical fit The effectiveness of the data presentation is enhanced if the relationship between the Y- and X-axis variables is established to obtain quantitative information.Figure 1Figure 1. Rate constants (solid points) and theoretical fits (solid line) based on Marcus electron transfer expression. From ref (4). Copyright 2020 American Chemical Society.High Resolution ImageDownload MS PowerPoint SlideCausationClick to copy section linkSection link copied!As per the definition, causation refers to an event or property caused by the occurrence of another variable or action. For example, if you want to show how a yield of a product (Y-axis) is dependent on the catalyst concentration (X-axis), you plot the data showing causality. Similarly, wavelength dependence of incident photon conversion efficiency (IPCE) of a solar cell shows how the wavelength of excitation causes the efficiency to change (Figure 2A). If one can establish a direct relationship between the two variables, it is possible to extract additional information. For example, in a kinetic analysis, one can graph (Figure 2B) pseudo first order rate constant (kobsd) versus quencher (Q) concentration. Such a plot can be used to obtain a second order rate constant (kq) of a bimolecular reaction using the expression, kobsd = k0 + kq[Q]. It is important to identify the relationship that can be used to describe the causality of the two variables in the data presentation. A detailed statistical explanation of correlation and causation can be found elsewhere. (7)Figure 2Figure 2. Examples of graphs showing causality between two variables. (A) Normalized incident photoconversion efficiency (IPCE) of 3D and 2D/3D perovskite solar cells in response to excitation wavelength. (B) The dependence of observed pseudo-first-order rate constant of biphenyl triplet decay (kobs) on the concentration of rubrene. From refs (5) and (6). Copyright 2022 and 2024 American Chemical Society.High Resolution ImageDownload MS PowerPoint SlideComparisonClick to copy section linkSection link copied!When there is no direct relationship between the two variables, it is not possible to associate them with correlation or causation. One such example is when we compare a measured property, such as a device performance or catalytic activity of different sets or samples. It is not unusual to see authors trying to line up these samples on the plot and show a trend by drawing a trendline (see, for example, Figure 3A). When there is no correlation or causation between the Y- and X-axis, such a trend line could be misleading. These plots represent an arbitrary trend since it can be varied by simply changing the order of the samples on the X-axis. While making performance comparison of such data, the best way is to present as a bar or column chart (Figure 3B) or simply plot the points on a Y–X plot without drawing a trend line.Figure 3Figure 3. Examples of sample property comparison using (A) trend line and (B) column graph. Since there is neither correlation or causality between the two variables, the data is better presented using a column chart. From ref (8). Copyright 2024 American Chemical Society.High Resolution ImageDownload MS PowerPoint SlideWe request our authors to undertake a careful examination of the data and establish the relationship between the variables before including them in the main figure. Including excessive data in figures without proper analysis simply drives the attention away from key results. Authors should consider including auxiliary data in the Supporting Information. Each figure composed with a distinct message makes the findings of the study stand out.Author InformationClick to copy section linkSection link copied!Corresponding AuthorPrashant V. Kamat, Editor-in-Chief, ACS Energy Letters, University of Notre Dame, Notre Dame, Indiana 46556, United States, https://orcid.org/0000-0002-2465-6819, Email: [email protected]NotesViews expressed in this editorial are those of the author and not necessarily the views of the ACS.AcknowledgmentsClick to copy section linkSection link copied!I would like to thank Prof. Gregory H. Hartland for helpful discussions.ReferencesClick to copy section linkSection link copied! This article references 8 other publications. 1Biegel, C. M.; Kamat, P. V. Ten Tips for Capturing Figures with Captions. ACS Energy Letters 2019, 4, 637– 638, DOI: 10.1021/acsenergylett.9b00253 Google Scholar1Ten Tips for Capturing Figures with CaptionsBiegel, Constance M.; Kamat, Prashant V.ACS Energy Letters (2019), 4 (3), 637-638CODEN: AELCCP; ISSN:2380-8195. (American Chemical Society) There is no expanded citation for this reference. >> More from SciFinder ®https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXjvFGlsbk%253D&md5=a37ce77ba803369998af564fb68e7d0f2Biegel, C. M.; Kamat, P. V. Five Common Pitfalls to Avoid while Composing Scientific Figures. ACS Energy Letters 2021, 6 (12), 4309– 4310, DOI: 10.1021/acsenergylett.1c02401 Google Scholar2Five Common Pitfalls to Avoid while Composing Scientific FiguresBiegel, Constance M.; Kamat, Prashant V.ACS Energy Letters (2021), 6 (12), 4309-4310CODEN: AELCCP; ISSN:2380-8195. (American Chemical Society) There is no expanded citation for this reference. >> More from SciFinder ®https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXisFersrjF&md5=fca0d48a25b6fa1685b73687c109008e3Kamat, P. V. The Lost Art of Composing Single-Panel Figures. ACS Energy Letters 2022, 7 (7), 2407– 2409, DOI: 10.1021/acsenergylett.2c01441 Google Scholar3The Lost Art of Composing Single-Panel FiguresKamat, Prashant V.ACS Energy Letters (2022), 7 (7), 2407-2409CODEN: AELCCP; ISSN:2380-8195. (American Chemical Society) There is no expanded citation for this reference. >> More from SciFinder ®https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38Xhs12htbbF&md5=454a59b5de61e33dd44523460c5fa06a4Saladin, M.; Maroncelli, M. Electron Transfer Kinetics between an Electron-Accepting Ionic Liquid and Coumarin Dyes. J. Phys. Chem. B 2020, 124, 11431– 11445Google ScholarThere is no corresponding record for this reference.5DuBose, J. T.; Szabó, G.; Chakkamalayath, J.; Kamat, P. V. Excited-State Transient Chemistry of Rubrene: A Whole Story. J. Phys. Chem. A 2022, 126 (40), 7147– 7158, DOI: 10.1021/acs.jpca.2c04499 Google ScholarThere is no corresponding record for this reference.6Szabó, G.; Kamat, P. V. How Cation Migration across a 2D/3D Interface Dictates Perovskite Solar Cell Efficiency. ACS Energy Letters 2024, 9, 193– 200, DOI: 10.1021/acsenergylett.3c02503 Google ScholarThere is no corresponding record for this reference.7Altman, N.; Krzywinski, M. Association, correlation and causation. Nat. Methods 2015, 12, 899– 900, DOI: 10.1038/nmeth.3587 Google ScholarThere is no corresponding record for this reference.8Xin, F.; Buyuker, I. S.; Zhou, H.; Guo, F.; Goel, A.; Bai, J.; Wang, F.; Whittingham, M. S. Importance of High Valence Element Nb in Ni-Rich Layered Cathodes for High-Voltage Lithium-Metal Batteries. ACS Energy Letters 2024, 9, 5172– 5178, DOI: 10.1021/acsenergylett.4c01230 Google ScholarThere is no corresponding record for this reference.Cited By Click to copy section linkSection link copied!This article has not yet been cited by other publications.Download PDFFiguresReferences Get e-AlertsGet e-AlertsACS Energy LettersCite this: ACS Energy Lett. 2025, 10, 3, 1540–1541Click to copy citationCitation copied!https://doi.org/10.1021/acsenergylett.5c00631Published March 14, 2025 Publication History Received 26 February 2025Accepted 27 February 2025Published online 14 March 2025Published in issue 14 March 2025Copyright © 2025 American Chemical Society. This publication is available under these Terms of Use. Request reuse permissionsArticle Views-Altmetric-Citations-Learn about these metrics closeArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated.Recommended Articles FiguresReferencesFigure 1Figure 1. Rate constants (solid points) and theoretical fits (solid line) based on Marcus electron transfer expression. From ref (4). Copyright 2020 American Chemical Society.High Resolution ImageDownload MS PowerPoint SlideFigure 2Figure 2. Examples of graphs showing causality between two variables. (A) Normalized incident photoconversion efficiency (IPCE) of 3D and 2D/3D perovskite solar cells in response to excitation wavelength. (B) The dependence of observed pseudo-first-order rate constant of biphenyl triplet decay (kobs) on the concentration of rubrene. From refs (5) and (6). Copyright 2022 and 2024 American Chemical Society.High Resolution ImageDownload MS PowerPoint SlideFigure 3Figure 3. Examples of sample property comparison using (A) trend line and (B) column graph. Since there is neither correlation or causality between the two variables, the data is better presented using a column chart. From ref (8). Copyright 2024 American Chemical Society.High Resolution ImageDownload MS PowerPoint SlideReferences This article references 8 other publications. 1Biegel, C. M.; Kamat, P. V. Ten Tips for Capturing Figures with Captions. ACS Energy Letters 2019, 4, 637– 638, DOI: 10.1021/acsenergylett.9b00253 1Ten Tips for Capturing Figures with CaptionsBiegel, Constance M.; Kamat, Prashant V.ACS Energy Letters (2019), 4 (3), 637-638CODEN: AELCCP; ISSN:2380-8195. (American Chemical Society) There is no expanded citation for this reference. >> More from SciFinder ®https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXjvFGlsbk%253D&md5=a37ce77ba803369998af564fb68e7d0f2Biegel, C. M.; Kamat, P. V. Five Common Pitfalls to Avoid while Composing Scientific Figures. ACS Energy Letters 2021, 6 (12), 4309– 4310, DOI: 10.1021/acsenergylett.1c02401 2Five Common Pitfalls to Avoid while Composing Scientific FiguresBiegel, Constance M.; Kamat, Prashant V.ACS Energy Letters (2021), 6 (12), 4309-4310CODEN: AELCCP; ISSN:2380-8195. (American Chemical Society) There is no expanded citation for this reference. >> More from SciFinder ®https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXisFersrjF&md5=fca0d48a25b6fa1685b73687c109008e3Kamat, P. V. The Lost Art of Composing Single-Panel Figures. ACS Energy Letters 2022, 7 (7), 2407– 2409, DOI: 10.1021/acsenergylett.2c01441 3The Lost Art of Composing Single-Panel FiguresKamat, Prashant V.ACS Energy Letters (2022), 7 (7), 2407-2409CODEN: AELCCP; ISSN:2380-8195. (American Chemical Society) There is no expanded citation for this reference. >> More from SciFinder ®https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38Xhs12htbbF&md5=454a59b5de61e33dd44523460c5fa06a4Saladin, M.; Maroncelli, M. Electron Transfer Kinetics between an Electron-Accepting Ionic Liquid and Coumarin Dyes. J. Phys. Chem. B 2020, 124, 11431– 11445There is no corresponding record for this reference.5DuBose, J. T.; Szabó, G.; Chakkamalayath, J.; Kamat, P. V. Excited-State Transient Chemistry of Rubrene: A Whole Story. J. Phys. Chem. A 2022, 126 (40), 7147– 7158, DOI: 10.1021/acs.jpca.2c04499 There is no corresponding record for this reference.6Szabó, G.; Kamat, P. V. How Cation Migration across a 2D/3D Interface Dictates Perovskite Solar Cell Efficiency. ACS Energy Letters 2024, 9, 193– 200, DOI: 10.1021/acsenergylett.3c02503 There is no corresponding record for this reference.7Altman, N.; Krzywinski, M. Association, correlation and causation. Nat. Methods 2015, 12, 899– 900, DOI: 10.1038/nmeth.3587 There is no corresponding record for this reference.8Xin, F.; Buyuker, I. S.; Zhou, H.; Guo, F.; Goel, A.; Bai, J.; Wang, F.; Whittingham, M. S. Importance of High Valence Element Nb in Ni-Rich Layered Cathodes for High-Voltage Lithium-Metal Batteries. ACS Energy Letters 2024, 9, 5172– 5178, DOI: 10.1021/acsenergylett.4c01230 There is no corresponding record for this reference.

The ability to tune the bandgap of metal halide perovskites through compositional alloying of the halide ion is of interest in designing tandem solar cells and light emitting displays. However, photoinduced migration of halide ions can significantly affect the device performance. One such property is photoinduced phase segregation in mixed halide perovskites (MHP), which forms bromide rich and iodide-rich domains. These domains act as charge carrier traps and lower the efficiency of perovskite-based devices.[1,2] The thermodynamic and redox properties of halide perovskites provide a strong driving force for hole trapping and oxidation of iodide species. These iodide species interact with hole transport layer, such as SpiroOMeTAD, changing its oxidation state. Thus, the mobility of halides and their susceptibility to hole-induced oxidation play a crucial role in determining the long-term stability of metal halide perovskite solar cells. The need to suppress halide ion migration as well as cation migration [3,4] to achieve long term stability and improve efficiency of perovskite solar cells will be discussed. References: [1] DuBose, J. T.; Kamat, P. V. Hole Trapping in Halide Perovskites Induces Phase Segregation, Accounts of Materials Research 2022, 3, 761-771. [2] DuBose, J. T.; Kamat, P. V. Energy Versus Electron Transfer: Managing Excited-State Interactions in Perovskite Nanocrystal–Molecular Hybrids, Chemical Reviews 2022, 122, 12475–12494. [3] Chakkamalayath, J.; Hiott, N.; Kamat, P. V. How Stable Is the 2D/3D Interface of Metal Halide Perovskite under Light and Heat?, ACS Energy Letters 2023, 8, 169-171. [4] Szabó, G.; Kamat, P. V., How Cation Migration across a 2D/3D Interface Dictates Perovskite Solar Cell Efficiency ACS Energy Letters 2024 9 (1), 193-200

Understanding charge carrier dynamics in two-dimensional (2D) semiconductors and their heterostructures is crucial for advancing their application in optoelectronic devices. In this work, two different 2D semiconductors, MoS2 and phenethylammonium lead iodide, (PEA)2PbI4 (a 2D perovskite), are physically coupled, and the excited-state dynamics are probed using femtosecond transient absorption measurements. Electron transfer from (PEA)2PbI4 to MoS2 and hole transfer from MoS2 to (PEA)2PbI4 were established by performing experiments at different excitation wavelengths (475 and 675 nm). The electron transfer step involved ultrafast hot-electron transfer (<1 ps) from (PEA)2PbI4 to MoS2, followed by thermalization. The electron and hole transfer between the 2D layers of the heterostructure was suppressed when a layer of poly(methyl methacrylate) (PMMA) was inserted between the two layers, thus breaking their interactions. The wavelength-dependent exciton and hot carrier dynamics in 2D heterostructures presented in this study have broad applications in energy conversion and optoelectronic devices.

ConspectusPhotoinduced energy and electron transfer processes offer a convenient way to convert light energy into electrical or chemical energy. These processes remain the basis of operation of thin film solar cells, light emitting and optoelectronic devices, and solar fuel generation. In many of these applications, semiconductor nanocrystals that absorb in the visible and near-infrared region are the building blocks that harvest photons and initiate energy or electron transfer to surface-bound chromophores. Such multifunctional aspects make it challenging to steer the energy transfer pathway selectively. Proper selection of the semiconductor nanocrystal donor requires consideration of the nanocrystal bandgap, along with the alignment of valence and conduction band energies relative to that of the acceptor, in order to achieve desired output of energy or electron transfer.In this Account, we focus on key aspects of managing energy flow from excited semiconductor nanocrystals to surface-bound chromophores. The singlet and triplet characteristics of the semiconductor nanoparticle enable tuning of energy transfer pathways through bandgap engineering. In addition to the alignment of energy levels between the semiconductor donor and the singlet/triplet energy levels of the acceptor dye, other parameters such as spectral overlap, surface binding through functional groups, and rate of competing energy transfer pathways all play integral roles in directing energy transfer. For example, in a prototypical halide perovskite nanocrystal-rhodamine dye assembly, singlet energy transfer is observed when the donor is a high-bandgap semiconductor (e.g., CsPbBr3, Eg= 2.47 eV). However, when the donor is a low-bandgap semiconductor (e.g., CsPbI3, Eg = 1.87 eV), one observes only triplet energy transfer. Tuning of the donor bandgap with mixed halide perovskites (e.g., CsPb(BrxI1-x)3) allows for populations of both singlet and triplet excited states of the acceptor dye. Additionally, triplet characteristics of the donor semiconductor nanocrystal can be further enhanced through Mn doping which places low-energy triplet-active states within the nanocrystal donor.The ability to steer energy transfer pathways in a semiconductor nanocrystal-dye assembly finds its use in the design of semiconductor-multichromophoric films. Such hybrid films can down-shift or up-convert incident photons and deliver emission at desired wavelengths. By selecting high energy donor (e.g., CsPbBr3) one can down-shift the incident photons through energy transfer cascade, as in the case of the CsPbBr3-rubrene-tetraphenyldibenzoperiflanthene (DBP) system to populate singlet excited DBP (perylene derivative). On the other hand, when the donor energy is low as in the case of CsPbI3-rubrene-DBP, one can populate singlet DBP via triplet-triplet annihilation. Thus, by steering energy transfer pathways, it is possible to manage the photon flow and obtain desired emission output. Fundamental understanding of excited state processes responsible for energy transfer will assist in designing light harvesting assemblies that can manage photon delivery effectively in display devices and other optoelectronic devices.

Modulation of singlet and triplet energy transfer from excited semiconductor nanocrystals to attached dye molecules remains an important criterion for the design of light-harvesting assemblies. Whereas one can consider the selection of donor and acceptor with favorable energetics, spectral overlap, and kinetics of energy transfer as a means to direct the singlet and triplet energy transfer pathways, it is not obvious how to control the singlet and triplet characteristics of the donor semiconductor nanocrystal itself. By doping CsPb(Cl0.7Br0.3)3 nanocrystals with Mn2+, we have now succeeded in increasing the triplet characteristics of semiconductor nanocrystals. The singlet and triplet energy transfer between excited Mn-CsPb(Cl0.7Br0.3)3 nanocrystals and a cyanine dye (4,5-benzoindotricarbocyanine) show the participation of band gap states in singlet energy transfer and Mn2+-activated states in triplet energy transfer. By tracking donor and acceptor emission as well as transient absorption spectral features, we were able to distinguish the two independent energy transfer pathways. Whereas singlet energy transfer from the exciton emission band remains unchanged (2%), increasing the concentration of Mn2+ in perovskite nanocrystals results in an increase of triplet energy transfer yield up to 17.5%. The ability to enhance the triplet transfer yield in CsPb(Cl0.7Br0.3)3 nanocrystals through Mn-doping opens up new opportunities to develop optoelectronic and display devices.

InfoMetricsFiguresRef. ACS Energy LettersVol 10/Issue 1Article This publication is free to access through this site. Learn More CiteCitationCitation and abstractCitation and referencesMore citation options ShareShare onFacebookX (Twitter)WeChatLinkedInRedditEmailJump toExpandCollapse EditorialJanuary 10, 2025Celebrating the 10th Year of ACS Energy LettersClick to copy article linkArticle link copied!Prashant V. Kamat*Prashant V. KamatUniversity of Notre Dame, Notre Dame, Indiana 46556, United States*[email protected]More by Prashant V. Kamathttps://orcid.org/0000-0002-2465-6819Open PDFACS Energy LettersCite this: ACS Energy Lett. 2025, 10, 1, 569–570Click to copy citationCitation copied!https://pubs.acs.org/doi/10.1021/acsenergylett.4c03409https://doi.org/10.1021/acsenergylett.4c03409Published January 10, 2025 Publication History Received 10 December 2024Accepted 10 December 2024Published online 10 January 2025Published in issue 10 January 2025editorialCopyright © 2025 American Chemical Society. This publication is available under these Terms of Use. Request reuse permissionsThis publication is licensed for personal use by The American Chemical Society. ACS PublicationsCopyright © 2025 American Chemical SocietySubjectswhat are subjectsArticle subjects are automatically applied from the ACS Subject Taxonomy and describe the scientific concepts and themes of the article.BatteriesChemical engineering and industrial chemistryEnergy storageSolar cellsSolar energyIt is with delight that we embark on the tenth year of ACS Energy Letters. Since the launch of the journal in 2016, we have built an enthusiastic energy community of authors, reviewers and readers. Their continued support has helped us to build a top-tier journal to disseminate new advances in energy research and discuss important scientific issues from the laboratory to the real world.We are pleased to engage with the passionate members of the scientific community who have made impressive progress in recent years to address clean energy challenges. The desire to reduce the carbon footprint has led to many innovative strategies to adopt renewable energy technologies. For example, perovskite solar cells, which showed an increase in efficiency from 14.1% in 2013 to 26.7% in 2024, are now being targeted for large-scale panel production. Si-perovskite-based tandem solar cells have made significant strides, reaching a record efficiency of 34.6%. Similarly, storage batteries have emerged from table-top devices to grid storage, and electrocatalysis is driving CO2 reduction on a pilot plant scale. The next phase of energy research is likely to be dominated with topics such as device stability of solar cells, display devices and electrolyzers, for long-term operation, fast charging of storage batteries, and recycling strategies for solar cells and storage batteries. Fundamental studies exploring properties of new materials for energy conversion and storage, and a better understanding of interfacial charge transfer processes in various devices (e.g., solar cells, storage batteries and LEDs), will also see a major growth in research.The growth of ACS Energy Letters during its first ten years can be seen from the increase in number of published articles as well as their growing impact (Figure 1). In addition to Letters, Perspectives and Reviews, we regularly publish Viewpoints and Energy Focus articles. These features offer our authors a unique opportunity to engage in scientific discussions. We also regularly feature Collections that compile key papers on an emerging topic. Each year, we also highlight contributions of women scientists along with their inspiring thoughts. Having anchored with these popular features during this early period, we plan to grow in the coming years by attracting new authors and readers.Figure 1Figure 1. Growth of ACS Energy Letters as seen from the published articles (all types) and citations. (* indicates incomplete data of 2024). Source: Web of Science, Clarivate Analytics, December 10, 2024.High Resolution ImageDownload MS PowerPoint SlideThe success of the journal stems from our Editorial Advisory Board members, who regularly provide feedback to our editorial team. Special thanks to EAB members Leif Hammarström, Uppsala University, Sweden, Dongling Ma, Institut National de la Recherche Scientifique, Canada, Bryan D. McCloskey, University of California Berkeley, USA, Iván Mora Seró, Universitat Jaume I, Spain, Edward (Ted) Sargent, Northwestern University, USA, and Yi-Jun Xu, Fuzhou University, China, who have completed their terms. We welcome new EAB members, Juan-Pablo Correa-Baena, School of Materials Science and Engineering, Georgia Institute of Technology, USA, Satish A. Patil, Solid State and Structural Chemistry Unit, Indian Institute of Science, India, Lorenzo Malavasi, Chemistry Department, University of Pavia, Italy, Ji-Hyun Jang, School of Energy and Chemical Engineering, UNIST, Republic of Korea, Partha P. Mukherjee, School of Mechanical Engineering, Purdue University, USA, Lakshminarayana Polavarapu, Department of Physical Chemistry, University of Vigo, Spain, Venkataraman Thangadurai, School of Chemistry, University of St Andrews, United Kingdom, and Ranjani Viswanatha, International Centre for Materials Science and New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, India. By having a good mix of senior and younger scientists from around the globe on our EAB board, we are able to seek a wide range of views on the journal's progress.I also take the opportunity to thank Raphaële Clément, University of California Santa Barbara, USA, who has completed her term as a Topic Editor. Her expertise in storage batteries helped us to publish several outstanding papers. Dinesh Kabra, Physics Department, Indian Institute of Technology Bombay, India, and Ya You, International School of Materials Science and Engineering and School of Materials Science and Microelectronics, Wuhan University of Technology, China, will now join our editorial team as Topic Editors. Filippo De Angelis, University of Perugia, Italy, and Yang-Kook Sun, Hanyang University, Republic of Korea, will now serve as Executive Editors. They will take additional responsibilities to manage the editorial manuscript flow and engage in improving the invited content of the journal. Together our editorial team will continue to work with our authors and reviewers to maintain high-quality topical content in the journal.As part of our 10th year celebration, we will publish several exciting features throughout the year. Two such Energy Focus features published in this issue include, (i) Women Scientists at the Forefront of Energy Research: Part 7 and (ii) A Conversation with Ib Chorkendorff.On behalf of our entire editorial team, I would like to wish everyone a happy new year!Author InformationClick to copy section linkSection link copied!Corresponding AuthorPrashant V. Kamat, Editor-in-Chief, ACS Energy Letters, University of Notre Dame, Notre Dame, Indiana 46556, United States, https://orcid.org/0000-0002-2465-6819, Email: [email protected]NotesViews expressed in this editorial are those of the author and not necessarily the views of the ACS.Cited By Click to copy section linkSection link copied!This article has not yet been cited by other publications.Download PDFFiguresReferences Get e-AlertsGet e-AlertsACS Energy LettersCite this: ACS Energy Lett. 2025, 10, 1, 569–570Click to copy citationCitation copied!https://doi.org/10.1021/acsenergylett.4c03409Published January 10, 2025 Publication History Received 10 December 2024Accepted 10 December 2024Published online 10 January 2025Published in issue 10 January 2025Copyright © 2025 American Chemical Society. This publication is available under these Terms of Use. 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Control of forward and back electron transfer processes in semiconductor nanocrystals is important to maximize charge separation for photocatalytic reduction/oxidation processes. By employing methyl viologen as the electron acceptor, we have succeeded in mapping the electron transfer from excited CsPbI3 nanocrystals to viologen as well as the hole trapping process. The electron transfer to viologen is an ultrafast process (ket = 2 × 1010 s-1) and results in the formation of extended charge separation as electrons are trapped at surface-bound viologen sites and holes at iodide sites. The I2─• formation, which is confirmed through the transient absorption at 750 nm, provides a convenient way to probe trapped holes and its participation in the back electron transfer process. By employing a series of mixed halide compositions, we were able to tune the bandgap and valence band energy of the perovskite donor. The back electron transfer rate constant (kbet = 1.3-2.6 × 107 s-1) is nearly three orders of magnitude smaller than that of forward electron transfer, thus extending the lifetime of the charge-separated state. The weak dependence of the back electron transfer rate constant on the valence band energy suggests that trapping of holes at halide (I or Br) sites is involved in the back electron transfer process. The ability to extend the lifetime of the charge-separated pair can offer new strategies to improve the redox properties of semiconductor-based photocatalytic systems.

Light induced processes at semiconductor/electrolyte interface lead to interfacial charge transfer processes. Electrochemistry offers a convenient approach to inject either electrons or holes at controlled potentials and thus influence the interfacial charge transfer processes. The talk will present two specific examples related to the operation of perovskite solar cells. The first example will present modulation of expulsion of iodine species from methyl halide perovskite film through controlled electrochemical bias. In the second phase we will identify different oxidation states of a hole conductor, Spiro OMeTAD and discuss the hole transport mechanism. The salient features of spectroelectrochemical investigation for improving the performance and stability of semiconductor solar cells will be discussed.