Tin-based perovskite solar cells (TPSCs) are strongly limited by Sn2+ oxidation and vacancy defects, which increase nonradiative losses and accelerate oxygen (O2)-related degradation. Here, mercaptoethylammonium bromide (ESABr) is introduced to regulate these coupled degradation processes. The thiol group buffers Sn2+/Sn4+ redox chemistry, while ammonium–iodide interactions stabilize the Sn-I framework and Br- compensates iodide-deficient sites. This combined regulation reduces Sn4+ accumulation and vacancy-associated trap states, suppressing defect-assisted recombination and improving carrier transport. More importantly, systematic simultaneous light and O2 (light/O2) aging measurements reveal slower electronic, chemical, and structural deterioration in ESABr-treated films, accompanied by reduced reactive O2 species generation. The optimized TPSCs achieve a power conversion efficiency of 15.09%. Encapsulated devices further exhibit a T80 lifetime of 896 h under maximum power point (MPP) tracking in ambient air, more than six times that of the control devices. These results connect redox and vacancy regulation with suppressed O2-related degradation, providing a mechanistic basis for improving the operational stability of tin perovskite photovoltaics.

For low-bandgap tin-lead (LBG Sn-Pb) devices, conventional organic hole transport materials (HTMs) fail to balance efficiency and stability, drawing attention to inorganic nickel oxide (NiOx) as a promising alternative. However, the inferior compatibility between NiOx and Sn-Pb perovskite severely hinders the development of NiOx-based Sn-Pb perovskite solar cells (PSCs) due to mismatched energy levels and oxidizing active species. Here, we propose a versatile strategy by introducing ammonium 2-hydroxyethanesulphonate (AHES) on NiOx films to fabricate efficient and stable NiOx-based Sn-Pb PSCs. The ─SO3 - in AHES could react with NiOx to regulate film morphology and optimize energy level alignment. Meanwhile, the presence of ─OH in AHES acting as Lewis base provides lone pair electrons to form hydrogen bond to modulate the crystallization process and improve film uniformity, resulting in enhanced lattice strength. As a result, our NiOx-based Sn-Pb device yields an efficiency of 22.98% (versus 20.02% for control) and retains 80% of the initial efficiency after continuous 1-sun illumination after 212 h (versus 90 h for control), which is among the best NiOx-based Sn-Pb PSCs. Finally, the champion four-terminal (4T) all-perovskite tandem solar cell achieves a remarkable efficiency of 30.38%.

Tin-based perovskite solar cells (Sn-PSCs) employing poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) gas hole transport layer represent one of the most promising architectures. However, their performance is severely limited by the insulating and hygroscopic...

The development of colloidal quantum dot solar cells (CQDSCs) is currently constrained by the substantial open-circuit voltage (Voc) deficit and intricate fabrication processes. Here, we present a simplified device architecture achieved by synergistically combining a direct-synthesis colloidal quantum dot (CQD) ink with a facile methanol/oxalic acid modification of the Poly(3,4-ethylenedoxythiophene):polystyrene sulfonate (PEDOT:PSS) interlayer. This strategy simultaneously addresses the poor wettability of aqueous PEDOT:PSS on hydrophobic PbS-EDT layers and initiates critical chemical optimization. By selectively removing insulating PSS, the treatment fosters a dense, electronically uniform fibrous network. Crucially, this optimized interlayer exhibits a work function shift from -5.30 to -5.15 eV, which reduces the hole extraction barrier to the Ag electrode from 0.51 to 0.36 eV. This favorable energy alignment extends the carrier lifetime from 0.54 to 2.37 ms and accelerates charge extraction. Consequently, the Voc is boosted from 649 to 742 mV, propelling the power conversion efficiency to 13.97%. This work offers a robust, process-compatible interfacial strategy to unlock stable, high-voltage CQDSCs.

Perovskite solar cells (PSCs) have achieved a power conversion efficiency (PCE) of over 27%, but further improvements of both PCEs and stability are needed for commercialization. One of the key factors hindering their development is the unpredictable residual strain in perovskites. The unstable octahedral structure of the perovskite cage leads to easy changes in bond lengths, bond angles, and crystal structure. It in turn generates, accumulates, and causes the non-uniform distribution of residual strain, ultimately affecting device performance. Therefore, given the versatility and precise tunability, residual strain engineering provides an effective pathway to optimize the performance of PSCs. This review summarizes the causes of residual strain during device fabrication and operation, qualitative/quantitative/auxiliary characterization methods, and various effective strain regulation methods in the past two years. Finally, unresolved scientific issues and future research directions in strain engineering are discussed. This comprehensive review aims to provide researchers with the latest advances in strain engineering, deepen fundamental understanding of strain effects, and eventually help enhance the performance of PSCs.

Tin (Sn)-based perovskite solar cells (PSCs) are promising candidates for low-toxicity photovoltaics. However, their performance remains limited by interfacial energy losses and cathode degradation. Here, we report a facile strategy of adopting ytterbium acetylacetonate (Yb(acac)3) as a solution-processed cathode buffer layer (CBL) to regulate the C60/Cu interface in Sn-based PSCs. The introduction of Yb(acac)3 improves energy-level alignment, suppresses charge accumulation and recombination, and facilitates electron extraction. Meanwhile, Yb(acac)3 forms a chemically anchored interlayer with C60 through pi-pi interactions, and its hydrophobic chelate structure hinders moisture ingress and iodide-ion migration, thereby enhancing the corrosion resistance of the Cu electrode. These interfacial effects are consistent with the strong Lewis acidity and coordination capability of Yb3+, which support stable interfacial binding and modified charge transport at the cathode interface. As a result, the optimized Sn-based PSCs deliver a champion efficiency of 14.92% together with substantially improved stability, maintaining 92% of the initial efficiency after 3000 h in N2 and similar to 85% after 350 h of continuous illumination in ambient air. This work provides an acetylacetonate-based interfacial engineering strategy for achieving high-performance Sn-based PSCs.

Reducing the volatile methylammonium cations (MA+) in low-bandgap tin-lead (Sn-Pb) perovskites can significantly enhance the durability of perovskite films, but at the cost of uncontrollable crystallization process and compromised device performance. Enhancing crystallization quality of perovskite films and minimizing both bulk and interface nonradiative recombination losses are crucial for improving the performance of Sn-Pb PSCs. Here, a multifunctional ionic compound, 1H-benzotriazol-1-yloxytris (dimethylamino) phosphonium hexafluorophosphate (BOP), simultaneously serves as an additive and surface passivator for MA-free Sn-Pb perovskites to enhance the device efficiency and stability. The crystallization is regulated by synergistic effects of benzotriazole (BTA) derivative groups and hexafluorophosphate anions (PF6- ) on BOP, leading to high-quality SnPb perovskite films with larger grains and fewer defects. The bulk doping of BOP combined with surface polishing further improves the film quality and minimizes the interfacial nonradiative recombination. Consequently, MA-free Sn-Pb PSCs without hole transport layer yield a champion efficiency of 22.23% with boosted stability. By coupling with a 1.77 eV wide-bandgap perovskite top sub cell, a four-terminal all-perovskite tandem solar cell with an efficiency of 28.45% has been achieved.

A novel bulk nano-heterojunction (BNH) architecture comprised of ZnO and NiO x nanocrystals is introduced for all-solution-processed, high performance ultraviolet photodetectors, enabling record external quantum efficiency and responsivity.

Tin-lead alloyed perovskite nanocrystals (PNCs) offer a promising pathway toward low-toxicity and air-stable light-emitting devices. However, substantial energetic disorder has thus far hindered their lighting applications compared to pure lead-based PNCs. A fundamental understanding of this disorder and its impact on optical properties is crucial for overcoming this limitation. Here, using temperature-dependent static and transient absorption spectroscopy, we meticulously distinguish the contributions of static disorder (including defects, impurities, etc.) and dynamic disorder (carrier-phonon interactions). We reveal how these disorders shape band-tail structure and ultimately influence inter-band carrier recombination behaviors. Surprisingly, we find that static and dynamic disorder primarily control band-tail defect states and bandgap renormalization, respectively, which together modulate fast carrier trapping and slow band-band recombination rates. Furthermore, we link these disorders to the tin-induced symmetry-lowering distortions in tin-lead alloyed PNCs. These findings illuminate critical design principles for highly luminescent, low-toxicity tin-lead PNCs, accelerating their adoption in optoelectronic applications.

Low-dimensional lead-free perovskite single crystals (SCs) have exhibited great potential in high-energy ionizing radiation detections owing to their outstanding sensitivity and charge transport properties. However, the preparation of chlorine-based SCs is more challenging due to their low solubility in organic solvents and acidic solutions. In this work, we report a universal growth strategy of hydrochloric acid-assisted temperature lowering for low-dimensional layered perovskite CsMnCl3·2H2O SCs. Compared with SCs prepared by solution evaporation crystallization, centimeter-sized SCs were achieved with ultrahigh crystal quality, showing a very small full width at half-maximum of 0.02° at the plane (002). Our layered perovskite CsMnCl3 2H2O X-ray detector shows unique anisotropic X-ray detecting performance at parallel and perpendicular to the (002) crystal plane. An ultralow detection limit of 9.3 nGyair s-1 has been obtained, which is significantly lower than the 5.5 μGyair s-1 required for regular medical diagnostics. Furthermore, the device shows enhanced stability with a slight degradation of 8% after storage in air ambient for 6 months. Our work suggests a promising approach to fabricate high-quality SCs for sensitive and stable X-ray detection applications.

Traditional p-type colloidal quantum dot(CQD)hole transport layers(HTLs)used in CQD solar cells(CQDSCs)are com-monly based on organic ligands exchange and the layer-by-layer(LbL)technique.Nonetheless,the ligand detachment and com-plex fabrication process introduce surface defects,compromising device stability and efficiency.In this work,we propose a solu-tion-phase ligand exchange(SPLE)method utilizing inorganic ligands to develop stable p-type lead sulfide(PbS)CQD inks for the first time.Various amounts of tin(II)iodide(SnI2)were mixed with lead halide(PbX2;X=I,Br)in the ligand solution.By pre-cisely controlling the SnI₂ concentration,we regulate the transition of PbS QDs from n-type to p-type.PbS CQDSCs were fabri-cated using two different HTL approaches:one with 1,2-ethanedithiol(EDT)-passivated QDs via the LbL method(control)and another with inorganic ligand-passivated QD ink(target).The target devices achieved a higher power conversion efficiency(PCE)of 10.93%,compared to 9.83%for the control devices.This improvement is attributed to reduced interfacial defects and enhanced carrier mobility.The proposed technique offers an efficient pathway for producing stable p-type PbS CQD inks using inorganic ligands,paving the way for high-performance and flexible CQD-based optoelectronic devices.

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is a widely used hole transport material in inverted tin-based perovskite solar cells (Sn-PSCs). However, the efficiency and stability of these Sn-PSCs that utilize PEDOT:PSS are unsatisfactory, partly due to concerns about their mismatched work functions, hydrophobicity, and chemical interactions. Here, we introduce a self-assembled monolayer (SAM), (2-(7H-dibenzo[c,g]carbazol-7-yl)ethyl) phosphonic acid (2PADCB) as a multifunctional buffer molecule at the buried PEDOT:PSS/Sn perovskite interface. The phosphate group in the 2PADCB molecule reacts with the sulfur atom on the thiophene ring in PEDOT:PSS. This reaction process effectively anchors the SAM molecule firmly to the surface of PEDOT:PSS. Additionally, it reduces the binding sites between PEDOT and PSS, alleviating the acidification of the PEDOT:PSS surface and the poor conductivity caused by excessive PSS. Furthermore, the presence of two additional benzene rings in the 2PADCB molecule terminal group increases the electron density around Sn2+, thereby inhibiting its oxidation. Additionally, the hydrophobic characteristics of the 2PADCB molecule mitigate moisture infiltration from PEDOT:PSS, thereby protecting the degradation of Sn perovskite. Consequently, the Sn-PSCs based on the PEDOT:PSS/2PADCB film achieve a champion efficiency of 14.7%, higher than that of their pristine counterpart (12.5%). Moreover, the 2PADCB molecule improves the stability of the device by maintaining 90% of its initial efficiency after 160 h under 1 Sun illumination. Such enhancement in efficiency and stability is mainly attributed to the improved interface quality with the 2PADCB molecule, leading to better carrier transport and suppressed charge recombination at the buried PEDOT:PSS/Sn perovskite interface. Our work suggests that introducing the 2PADCB molecule at the PEDOT:PSS/perovskite interface is a promising method for efficient and stable Sn-PSCs.

Antimony selenosulfide, denoted as Sb2(S,Se)3, has garnered attention as an eco-friendly semiconductor candidate for thin-film photovoltaics due to its light-absorbing properties. The power conversion efficiency (PCE) of Sb2(S,Se)3 solar cells has recently increased to 10.75%, but significant challenges persist, particularly in the areas of open-circuit voltage (Voc) losses and fill factor (FF) losses. This study delves into the theoretical relationship between Voc and FF, revealing that, under conditions of low Voc and FF, internal resistance has a more pronounced effect on FF compared to non-radiative recombination. To address Voc and FF losses effectively, a phased optimization strategy was devised and implemented, paving the way for Sb2(S,Se)3 solar cells with PCEs exceeding 20%. By optimizing internal resistance, the FF loss was reduced from 10.79% to 2.80%, increasing the PCE to 12.57%. Subsequently, modifying the band level at the interface resulted in an 18.75% increase in Voc, pushing the PCE above 15%. Furthermore, minimizing interface recombination reduced Voc loss to 0.45 V and FF loss to 0.96%, enabling the PCE to surpass 20%. Finally, by augmenting the absorber layer thickness to 600 nm, we fully utilized the light absorption potential of Sb2(S,Se)3, achieving an unprecedented PCE of 26.77%. This study pinpoints the key factors affecting Voc and FF losses in Sb2(S,Se)3 solar cells and outlines an optimization pathway that markedly improves device efficiency, providing a valuable reference for further development of high-performance photovoltaic applications.

Iodine-doped bromide perovskite single crystals (IBPSCs) have important applications in optoelectronic fields, such as in solar cells. Currently, much research has aimed to study the phase separation phenomenon and device performance improvements in IBPSCs. However, important intrinsic photoexcited carrier dynamics are often overlooked in IBPSCs. Here, we explored the photoexcited carrier dynamics in typical iodine-doped MAPbBr(3) single crystals using the excitation intensity-dependent steady-state photoluminescence (PL) and time-resolved photoluminescence (TRPL) technique. We found that the trap state density changes with an increase in the amount of doped iodine. Further, we noticed that there is an influence of carrier diffusion on the photoexcited carrier dynamics, and then, we evaluated the carrier diffusion coefficients and recombination constants via numerical simulations of the PL kinetics. Consequently, we found that the electron shallow trap-related carrier behaviors substantially impacted the PL kinetics. Our results greatly facilitate a deeper understanding of the fundamental characteristics of mixed halide perovskite material.

The development of tin-lead alloyed halide perovskite nanocrystals (PNCs) is highly desirable for creating ultrastable, eco-friendly optoelectronic applications. However, the current incorporation of tin into the lead matrix results in severe photoluminescence (PL) quenching. To date, the precise atomic-scale structural origins of this quenching are still unknown, representing a significant barrier to fully realizing the potential of these materials. Here, we uncover the distinctive defect-related microstructures responsible for PL quenching using atomic-resolution scanning transmission electron microscopy and theoretical calculations. Our findings reveal an increase in point defects and Ruddlesden-Popper (RP) planar faults with increasing tin content. Notably, the point defects include a spectrum of vacancies and previously overlooked antisite defects with bromide vacancies and cation antisite defects emerging as the primary contributors to deep-level defects. Furthermore, the RP planar faults exhibit not only the typical rock-salt stacking pattern found in pure Pb-based PNCs but also previously undocumented microstructures rich in bromide vacancies and deep-level cation antisite defects. Direct strain imaging uncovers severe lattice distortion and significant inhomogeneous strain distributions caused by point defect aggregation, potentially breaking the local force balance and driving RP planar fault formation via lattice slippage. Our work illuminates the nature and evolution of defects in tin-lead alloyed halide perovskite nanocrystals and their profound impact on PL quenching, providing insights that support future material strategies in the development of less toxic tin-lead alloyed perovskite nanocrystals.

Despite much effort being made, the origin of Stokes shift in colloidal quantum dot (CQD) solutions is still debatable to date, particularly in the case of QD films, which are typically used as active layers in the optoelectronic devices but have been rarely explored. Herein, we demonstrate that for QD solutions, the main origin contribution to the Stokes shift is the confined electron state (CES). In the case of QD films, in addition to the aforementioned CES, for the first time, we found that the Stokes shift is also affected by the electronic coupling strength between adjacent QDs. Overall, an improved understanding of the origin of the Stokes shift in lead sulfide (PbS) QD solutions and films can provide the key fundamental knowledge for realizing efficient optoelectronic devices.

The efficient harnessing of hot carriers holds transformative potential for next-generation optoelectronic devices. Halide perovskites, with their remarkably long carrier lifetimes exceeding 10 picoseconds, stand at the forefront of this research frontier. Yet, a fundamental paradox persists: why does efficient hot carrier capture remain elusive despite these extended lifetimes? Here, this conundrum is unraveled by constructing a donor-acceptor model system: perovskite nanocrystal and fullerene hybrids. It is demonstrated that the challenge lies not only in the carrier lifetime itself but in the nature of the coupling between donor and acceptor components. Remarkably, it is discovered that the formation of ground-state complexes, with effective coupling across a wide energy range, not only overcomes the initially forbidden hot carrier capture within these hybrids but also dramatically enhances it, achieving a approximate to 76% hot carrier capture efficiency. This finding shifts the paradigm of hot carrier capture from extending carrier lifetimes to engineering donor-acceptor coupling, illuminating a path toward practical hot carrier applications.

Inorganic tin (Sn) perovskite nanocrystals offer a promising solution to the potential toxicity concerns associated with their established lead (Pb)-based counterparts. Yet, achieving their superior stability and optoelectronic properties remains an ongoing challenge. Here, we report a synthesis of high-symmetry α-phase CsSnI3 nanocrystals with an ultralong 278 ns carrier lifetime, exceeding previous benchmarks by 2 orders of magnitude through meticulous Sn(IV) control. The nanocrystals demonstrate excellent colloidal stability, uniform monodispersity, and a distinct exciton peak. Central to these outcomes is our designed solid-liquid antioxidation suspension of tri-n-octylphosphine (TOP) and zerovalent tin (Sn(0)) that fully addresses the unique coexisting oxygen-driven and solvent-driven Sn oxidation mechanisms in Sn perovskite nanocrystal synthesis. We uncover the largely undervalued function of TOP in mitigating oxygen-driven Sn oxidation and introduce Sn(0) powder to generate a synergistic antioxidation function with TOP, significantly reducing Sn(IV)-induced defects and distortions and contributing to enhanced optoelectronic properties. Strikingly, this approach also profoundly impacts inorganic Sn-Pb perovskite nanocrystals, boosting lifetimes by 2 orders of magnitude and increasing photoluminescence quantum yield over 100-fold to 35%. Our findings illuminate the potential of Sn-based nanocrystals for optoelectronic applications.

Nowadays, the extensively used lead sulfide (PbS) quantum dot (QD) hole transport layer (HTL) relies on layer-by-layer method to replace long chain oleic acid (OA) ligands with short 1,2-ethanedithiol (EDT) ligands for preparation. However, the inevitable significant volume shrinkage caused by this traditional method will result in undesired cracks and disordered QD arrangement in the film, along with adverse increased defect density and inhomogeneous energy landscape. To solve the problem, a novel method for EDT passivated PbS QD (PbS-EDT) HTL preparation using small-sized benzoic acid (BA) as intermediate ligands is proposed in this work. BA is substituted for OA ligands in solution followed by ligand exchange with EDT layer by layer. With the new method, smoother PbS-EDT films with more ordered and closer QD packing are gained. It is demonstrated stronger coupling between QDs and reduced defects in the QD HTL owing to the intermediate BA ligand exchange. As a result, the suppressed nonradiative recombination and enhanced carrier mobility are achieved, contributing to approximate to 20% growth in short circuit current density (Jsc) and a 23.4% higher power conversion efficiency (PCE) of 13.2%. This work provides a general framework for layer-by-layer QD film manufacturing optimization. To solve the problem of volume shrinkage and inhomogeneous energy landscape, a novel method for PbS-EDT HTL preparation using small-sized benzoic acid (BA) as intermediate ligands is proposed in this work. Stronger coupling between QDs and reduced defects in the QD HTL are realized. Nearly 20% growth in Jsc and a 23.4% higher PCE of 13.2% are achieved. image

Cs2NaInCl6 double perovskites, which have excellent photoelectric conversion properties and are non-toxic and lead-free, have recently gained significant attention. In particular, double-perovskite quantum dots (QDs) are viewed as a promising material for optoelectronic device applications. Ligands such as oleic acid (OA) and oleylamine (OAm) are essential for the synthesis of perovskite QDs, but their specific roles in double-perovskite QDs remain unclear. In this study, we have investigated the binding of OA and OAm to Cs2NaInCl6 QDs through FTIR and NMR and their effects on the surface defect reduction and stability improvement for Cs2NaInCl6 QDs. We found that only OAm was bound to the QD surfaces while OA was not. The OAm has a significant effect on the photoluminescence quantum yield (PLQY) improvement by passivating the QD surface defects. The stability of the QDs was also evaluated, and it was observed that OA played a significant role in the stability of the QDs. Our findings provide valuable insights into the roles of ligands in influencing the photophysical properties and stability of lead-free double-perovskite QDs.