We passivate TiO 2 surface with alkali metal fluorides and dilute HCl, enhancing perovskite device stability. The optimized device maintains 88% of its initial efficiency after 1000 hours of continuous light soaking.

Although X-ray diffraction (XRD) technology has played an essential role in studying the lattice strain of perovskite solar cells (PSCs), accurate construction of the relationship between strains and PSC performance remains challenging due to its limitations. This study investigates the spatial strain distributions of perovskite films on electron transport layers (ETLs) with different surface free energies (γss) through confocal micro-Raman spectroscopy (CMRS) mapping and XRD technology. Results showed that CMRS mapping could more effectively reflect the distribution and size of spatial strain. Uniformed spatial strain with larger grain and preferred orientations can be realized over substrates with optimized γs, corresponding to recombination suppression and interfacial carrier extraction enhancement and significantly reducing open-circuit voltage (VOC) deficits. Optimized PSCs achieve the power conversion efficiency (PCE) of 24.64% and demonstrate excellent compatibility toward large-area or flexible applications, with 20.66% and 22.13% PCEs based on perovskite mini-module and flexible PSCs, respectively.

Hypothesis formulation is a creative process fundamental to scientific exploration, and there is an increasing interest in using generative AI to augment humans in this regard. This study explores the potential of large language models, particularly ChatGPT, to generate viable hypotheses within experimental materials science. Focusing on the subdomain of surface passivation of hybrid perovskites, our aim is to identify untested molecules capable of reducing surface recombination and thereby boost the efficiency of perovskite solar cells. By utilizing ChatGPT to brainstorm ideas and formulate new hypotheses, we identify polyallylamine (PAA) as a potential surface modifier, which is a molecule we would not have considered otherwise. Subsequent experimental investigations demonstrate PAA to indeed be effective in decreasing recombination rates and improving device efficiency. This demonstrates a potent synergy between human expertise and AI capabilities also in more intellectual and intuitive facets of the scientific process, such as hypothesis generation.

In the commercial development of perovskite solar cells, the main challenge lies in achieving efficient devices with high stability. Additive engineering in polycrystalline perovskites is considered as an effective approach to address this challenge by passivating surface defects and reducing carrier losses associated with these defects. In this work, the passivation effect of molecules with different side chain groups on perovskites and the role of binding energy in mitigating carrier loss are studied. The findings reveal that the thiophene group is particularly effective in passivating defects and enhancing hole transport. Consequently, devices treated with 2-thienylmethylamine hydrochloride (TMAC) demonstrate a champion power conversion efficiency (PCE) of 24.63%. Furthermore, these TMAC-treated devices exhibit remarkable stability, maintaining over 93.13% of their initial efficiencies after 1200 h of continuous illumination under maximum power point tracking (MPPT). This research presents a pathway to enhance the optoelectronic performance and stability of perovskite solar cells.

The buried interface between the electron transport layer (ETL) and the perovskite layer plays a crucial role in enhancing the power conversion efficiency (PCE) and stability of n–i–p type perovskite solar cells (PSCs). In this study, the interface between the chemical bath deposited (CBD) titanium oxide (TiO2) ETL and the perovskite layer using multi‐functional potassium trifluoromethyl sulfonate (SK) is modified. Structural and elemental analyses reveal that the trifluoromethyl sulfonate serves as a crosslinker between the TiO2 and the perovskite layer, thus improving the adhesion of the perovskite to the TiO2 ETL through strong bonding of the ─CF3 and ─SO3− terminal groups. Furthermore, the multi‐functional modifiers reduced interface defects and suppressed carrier recombination in the PSCs. Consequently, devices with a champion PCE of 25.22% and a fill factor (FF) close to 85% is achieved, marking the highest PCE and FF observed for PSCs based on CBD TiO2. The unencapsulated device maintained 81.3% of its initial PCE after operating for 1000 h.

Formamidinium lead triiodide (FAPbI3)-rich perovskite absorbers have emerged as the frontrunners for the development of perovskite solar cells (PSCs), but pristine FAPbI3 absorber exhibits phase instability because of external stressors during device manufacture and operation. In this work, we systematically study the function of a trace amount of phenyltrimethylammonium chloride (PTAC) additive in FAPbI3-based perovskites. The introduced PTAC have a strong electrostatic interaction with perovskite because of the coordination of electronrich benzene ring unit and under-coordinated Pb2+, which leads to the decrease of the trap density and the release of the lattice strain. Simultaneously, the increased work function of modulated film optimizes the band alignment, promoting carrier transport and reducing nonradiative recombination, thereby improving the opencircuit voltages and fill factors. Consequently, the modulated PSCs achieve a champion power conversion efficiency of 24.51%, and exhibit much better stability by retaining 90% of their initial efficiency after 1000 hours constant illumination under maximum power point tracking measurement.

The best research-cell efficiency of perovskite solar cells (PSCs) is comparable with that of mature silicon solar cells (SSCs); However, the industrial development of PSCs lags far behind SSCs. PSC is a multiphase and multicomponent system, whose consequent interfacial energy loss and carrier loss seriously affect the performance and stability of devices. Here, by using spinodal decomposition, a spontaneous solid phase segregation process, in situ introduces a poly(3-hexylthiophene)/perovskite (P3HT/PVK) heterointerface with interpenetrating structure in PSCs. The P3HT/PVK heterointerface tunes the energy alignment, thereby reducing the energy loss at the interface; The P3HT/PVK interpenetrating structure bridges a transport channel, thus decreasing the carrier loss at the interface. The simultaneous mitigation of energy and carrier losses by P3HT/PVK heterointerface enables n-i-p geometry device a power conversion efficiency of 24.53% (certified 23.94%) and excellent stability. These findings demonstrate an ingenious strategy to optimize the performance of PSCs by heterointerface via Spinodal decomposition.

A dopant-free polymeric hole selective contact (HSC) layer is ubiquitous for stable perovskite solar cells (PSCs). However, the intrinsic nonwetting nature of the polymeric HSC impedes the uniform spreading of the perovskite precursor solution, generating a terrible buried interface. Here, we dexterously tackle this dilemma from the perspective of dispersive and polar component surface energies of the HSC layer. A novel triarylamine-based HSC material, poly[bis(4-phenyl)(2,4-dimethoxyphenyl)amine] (2MeO-PTAA), was designed by introducing the polar methoxy groups to the para and ortho positions of the dangling benzene. These nonsymmetrically substituted electron-donating methoxy groups enhanced the polar components of surface energy, allowing more tight interfacial contact between the HSC layer and perovskite and facilitating hole extraction. When utilized as the dopant-free HSC layer in inverted PSCs, the 2MeO-PTAA-based device with CH3NH3PbI3 as the absorber exhibited an encouraging power conversion efficiency of 20.23% and a high fill factor of 84.31% with negligible hysteresis. Finally, a revised detailed balance model was used to verify the drastically lessened surface defect-induced recombination loss and shunt resistance loss in 2MeO-PTAA-based devices. This work demonstrates a facile and efficient way to modulate the buried interface and shed light on the direction to further improve the photovoltaic performance of inverted PSCs with other types of perovskites.

Surface defects have been a primary limitation for perovskite solar cells (PSCs). Herein, the introduction of 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6) into the perovskite surface with the help of isopropanol (IPA) solvent can passivate the surface defects. The surface reconstruction of perovskite caused by IPA makes it easier for [BMIM](+) to passivate uncoordinated Pb2+ defects, [PF](6)(-) to more easily replace and compensate unstable I-/Br- ions and I-/Br- vacancies. This forms large perovskite grains and island-like Cs-0.05(MA(0.12)FA(0.88))(0.95)Pb(I0.88Br0.12)(3-x)(PF6)(x) interlayers, which significantly reduces the defect-states density and inhibits recombination, and the energy barrier for the perovskite and the hole transport layer is also lowered. As a result, the open-circuit voltage was elevated from 1.112 to 1.181 V, and the efficiency for solar cells was also increased from 19.01% to 21.51%. In addition, the surface treatment of the hydrophobic BMIMPF6 can isolate the erosion of moisture and obtain better stability.

Solar energy is clean, open, and infinite, but solar radiation on the earth is fluctuating, intermittent, and unstable. So, the sustainable utilization of solar energy needs the complementary combination of high-efficient energy conversion and low-loss energy storage technologies. Hence, a photocapacitor integrated with photo-electrical conversion and electric-chemical storage functions in single device is a cost-effective, volume-effective and functional-effective optimal choice. However, the highest reported conversion storage efficiency of single device is less than 13 %. Here, we investigate the relationship among various efficiencies of photocapacitors during conversion storage process, and propose a function portfolio management concept. Accordingly, a three-terminal photocapacitor integrated with perovskite solar cell and symmetrical supercapacitor units is designed. By harmonizing the energy matching between conversion and storage units and seeking the maximum power points coincide and the maximum efficiency points synchronize, the solar energy conversion storage efficiency of the integrated photocapacitor surpasses milestone of 20 %.

The perovskite solar cells (PSCs) is one of the fastest growing photovoltaic technology. However, the further improvement of performance and stability is the bottleneck issue of its large-scale manufacturing. The controllable oxidation of spiroOMeTAD is significant for high-performance PSCs. Here, a low-cost and facile strategy by doping 3-Chloroperoxybenzoic acid (m-CPBA) into spiroOMeTAD is demonstrated. The addition of m-CPBA accelerates the oxidation of spiroOMeTAD, produces more carriers, improves the hole conductivity, and reduces defects and carrier non-radiative recombination. On the other hand, the modification of m-CPBA adjusts the HOMO of hole transport layer (HTL), makes more match the energy array between HTL and perovskite layer, and reduces energy loss at interface. Consequently, the m-CPBA optimized PSCs achieves a power conversion efficiency (PCE) of 23.34% with an outstanding fill factor (FF) over 84%, along with excellent environmental stability.

The practical applications of perovskite solar cells (PSCs) are limited by the further improvement of their stability and performance. Interface engineering is a promising strategy to solve these pain points. Herein, we design (R)-(-)-1-cyclohexylethylamine iodide (R-CEAI), composed of positively charged hydrophobic R-CEA+ and negatively charged I-, to post-treat the interface of 3D mixed-cation/halide perovskite with assist one of isopropyl alcohol (IPA). R-CEAI treatment not only passivates the defects at surface and grain boundaries of perovskite, but also in-situ grows quasi 2D Ruddlesden-Popper perovskite at the interface between 3D perovskite and hole transport layer, which reduces trap density of states, tunes energy level and alleviates lattice distortion. As a result, R-CEAI treated 2D/3D PSCs yield a champion PCE of 22.52%, with an improved open-circuit voltage of 1.195 V and retain 84.34% of their initial efficiency in long-term stability test, while the pristine device provides a PCE of 19.43% with only 54.30% retention.

Accurate interface engineering can effectively inhibit iodide ion migration, thereby improving the stability and photovoltaic performance of perovskite solar cells (PvSCs). The time‐of‐flight secondary‐ion mass spectrometry reveals that in an aged n–i–p‐type PvSC, the iodide ions will move toward the rear side and enter the FTO cathode. In this regard, the authors describe a simple thermal evaporation strategy for introducing an NdCl3 interface layer (NdCl3‐IL) at the rear interface of perovskites to interdict the iodine ion migration pathway, leading to reduced trap densities throughout the whole perovskite region. As a result, a boosted open‐circuit voltage (VOC) is achieved, resulting in power conversion efficiency (PCE) up to 22.16% with negligible hysteresis. The NdCl3‐IL also enhances the device stability, maintaining 83% of initial PCE after the maximum‐power‐point tracking test for 100 h. More encouragingly, a certified PCE of 21.68% is demonstrated on a large‐area (1 cm2) device with combined 2D/3D passivation strategies.

The vast majority of high-performance perovskite solar cells (PSCs) are based on a formamidinium lead iodide (FAPbI(3))-dominant composition. Nevertheless, the FA-based perovskite films suffer from undesirable phase transition and defects-induced non-ideal interfacial recombination, which significantly induces energy loss and hinders the improvement of device performance. Herein, we employed 4-fluorophenylmethylammonium iodide (F-PMAI) to modulate surface structure and energy level alignment of the FA-based perovskite films. The superior optoelectronic films were obtained with reduced trap density, pure alpha-phase FAPbI(3) and favorable energy band bending. The lifetime of photogenerated charge carriers increased from 489.3 ns to 1010.6 ns, and a more "p-type" perovskite film was obtained by the post-treatment with F-PMAI. Following this strategy, we demonstrated an improved power conversion efficiency of 22.59% for the FA-based PSCs with an open-circuit voltage loss of 399 mV. (C) 2021 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.

Photocapacitor integrating both energy harvest and storage functions into a single device is a frontier research orientation, which facilitates the efficient and sustainable utilization of green energy.

Perovskite solar cells (PSCs) have made great strides as new generation photovoltaic technology. The hole transport materials (HTMs) play an indispensable part in high performing PSCs. Spiro-OMeTAD (Spiro) is the most frequently used HTM. However, pristine Spiro has low conductivity and poor hole mobility. Additives engineering is considered as an effective strategy to solve the dilemma. Here, an organic peroxide additive tert-butyl peroxybenzoate (TBPB) is introduced into Spiro. TBPB not only promotes the rapid oxidation of Spiro to generate more carriers, but also tunes the HOMO of Spiro to achieve proper energy level matching with perovskite layer. Consequently, the TBPB modified device achieves a power conversion efficiency (PCE) of 23.45% with high fill factor (FF) of 81.97%. Meanwhile, the modification of TBPB improves the hysteresis effect, reproducibility and environmental stability of the device. After 80 days of storage in ambient air (RH 26%), the TBPB-doped unencapsulated PSCs still maintained 88.8% of their initial efficiency.

Methylammonium-free perovskite solar cells have attracted a great deal of attention owing to the optimal bandgap towards the Shockley-Queisser optimum and the improved thermal stability of FAPbI3 based perovskite. Nevertheless, MA-free devices suffer from a large voltage deficit further limiting the improvement of performance. Herein, a surface reconstruction strategy to constituted 2D/3D heterojunction via imidazole hydrobromide post-treatment is proposed. The formation 2D/3D heterostructure endows the MA-free perovskite film with decent energy-level alignment and reduced non-radiative recombination, which enhances the quasi-Fermi level splitting further to minimize the voltage deficit in the device. Consequently, this strategy leads to a significantly increased power conversion efficiency of 23.25% for FA0.9Cs0.1PbI3 perovskite solar cells, along with an optimal voltage deficit of 0.384 V. This work may trigger the development of surface reconstruction that constitutes suitable interface to the perovskite film to maximize the open-circuit voltage and thus the power conversion efficiency of perovskite solar cells.

Perovskite solar cells (PSCs) have received widespread attention due to their excellent photovoltaic character-istics. However, the nonradiative recombination of carriers induced by defects limits the stability and perfor-mance of PSCs. Interface and additive engineering are good medicine to cure the disease. Herein, formamidine acetate (FAAc) as interfacial additive is introduced to the TiO2/perovskite interface. The connection of the FA(+) between the TiO2 and perovskite promotes electron transport, and the amino group (-NH2) and carboxyl group (-COOH) of FAAc passivates the defect at TiO2/perovskite interface. Meanwhile, the FAAc modification tunes the energy array and improves crystal quality of perovskite. In consequence, the PSC based on FAAc-modified TiO2 achieves the best power conversion efficiency (PCE) of 20.47%, accompanied with excellent stability and mitigated hysteresis, while PCE of the pristine PSC is 18.30%.

The ionic properties of components determine that perovskite films will generate numerous charged surface defect under continuous high-temperature annealing, resulting in suboptimal performance and poor stability of perovskite solar cells (PSCs). Based on the principle of Lewis acid-base coordination, 1,8-naphthyridine (1,8-ND) with electron-rich structure was used to form complexes with Pb2+ ions, and high-quality 2D/3D perovskite films with effective defect passivation were prepared by surface modification. Benefiting from suppressed nonradiative recombination, extended carrier lifetime, modified charge transport, improved hydrophobic properties and the optimized phase stability of alpha-FAPbI3, 1,8-ND modified 2D/3D PSCs with negligible hysteresis and satisfactory stability achieved a champion power conversion efficiency of 23.8% whose open circuit voltage was significantly improved from 1.09 V to 1.15 V, providing a resultful strategy to passivate surface defect while constructing 2D/ 3D perovskite.

While serious stability issues impede the commercialization of perovskite solar cells (PSCs), two-dimensional (2D) perovskites based on fluorinated bulky cations have emerged as more intrinsically stable materials. However, the influence of fluorination degree of the bulky aromatic cation on the performance of resulting PSCs has not been scrutinized. Here, 2D perovskites (FxPEA)2PbI4 (x = 1, 2, 3, 5) are grown in situ on the surface of the three-dimensional (3D) perovskite and demonstrate effective passivation of the surface defects of 3D perovskite. The power conversion efficiency (PCE) of the optimized devices were boosted from 20.75% for the control device to 21.09%, 22.06%, 22.74% and 21.86% for 2D/3D devices treated with 4-fluorophenethylamine iodide, 3,5-difluorophenylethylamine iodide, 2,4,5-trifluoroethylphenylethylamine iodide, and 1,2,3,4,5-pentafluorophenylethylamine iodide, respectively. We firstly reported two unexplored RP-type layered perovskites with F2PEAI and F3PEAI as bulky cations. The combined experimental and theoretical analysis revealed the reasons behind the various morphology, device performances, dynamic behavior, and humidity stability. The best performing F5PEAI-treated device retaining 95.0% of its initial PCE under ambient atmosphere (with RH of 60% ± 5%) without encapsulation for 300 h storage. This work provides useful guidance for selecting fluorinated bulky cations with different molecular electronic properties, which will play an essential role in further improving the performance/stability of PSCs for the sake of further commercialization.