Local contact passivation (LCP), a technique extensively employed in silicon solar cells, has recently been recognized as an efficient approach to mitigating interfacial recombination in perovskite solar cells (PSCs). However, the underlying physical mechanisms and design principles remain insufficiently understood in perovskite devices. Here, we develop a rigorous optoelectronic simulation model to systematically investigate PSCs featuring a nanoscale LCP structure at the electron transport layer/perovskite interface. Our simulations reveal that LCP-based PSCs with positive fixed charges, high areal coverage, and small feature sizes can effectively suppress interface recombination and improve device efficiency. Furthermore, the introduction of a LCP structure enables greater tolerance to defect density at the perovskite/transport layer interface and to variations in energy band alignment, maintaining high performance even under elevated defect densities or misaligned energy bands. Additionally, LCP-based PSCs with positive fixed charges exhibit suppressed ion migration due to the formation of a favorable local electric field that reduces ion accumulation and thus mitigates carrier recombination. By integrating these design strategies, a clear performance-enhancement pathway is demonstrated, showing an improvement in device efficiency from 26.42% to 27.46%. This work provides practical design guidelines for leveraging LCP to achieve high-efficiency PSCs.

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.

Low-bandgap (E-g similar to 1.25 eV) tin-lead perovskite solar cells hold great potential for constructing efficient all-perovskite tandem solar cells (TSCs). However, rapid degradation of perovskite precursor solutions, owing to easy oxidation of Sn2+, remains a major challenge. Here we elucidate oxidation pathways in Sn-Pb perovskite precursors. We further introduce basic amino acids and basic amino acids sulfate (BAAS) as proton scavengers, which stabilize the ink for over 300 days. BAAS neutralizes excess protons to mitigate dimethyl sulfoxide-driven oxidation reactions, whereas sulfate ions coordinate Sn2+ to passivate defects and regulate crystallization. The optimized low-bandgap perovskite solar cell achieves a power conversion efficiency of 24.06% with an open-circuit voltage of 0.905 V, enabling two-terminal all-perovskite TSCs with a power conversion efficiency of 30.24% (certified 29.56%). The BAAS-passivated TSCs retain over 85% of their initial performance after 1,000 hours of the maximum power point operation under 1-sun illumination.

Solution-processed SnO2 nanoparticles are promising nonfullerene electron transport materials, yet their performance in low-bandgap (LBG) tin-lead perovskite solar cells (Sn-Pb PSCs) is hindered by inadequate charge transport and interface energy misalignment. To address these issues, we developed a SnO2-graphene quantum dot (GQD) electron transport layer (ETL) by functionalizing solution-processed SnO2 with GQDs. Both theory calculations and experiments indicate the electron-bridging role of GQDs in perovskite/GQD-SnO2 heterojunction, greatly facilitating directional charge transfer. Moreover, GQDs play a dual role by passivating defects on both SnO2 and perovskite surfaces, while optimizing the energy level alignment at this critical interface. Consequently, the optimized LBG Sn-Pb PSCs exhibit significantly enhanced voltage and fill factor, achieving a champion efficiency of 23.38% with robust stability under ISOS-L-1 and ISOS-D-2 protocols. When integrated into all-perovskite tandem solar cells, the optimized device delivers a promising efficiency of 29.40%. This work enables the first viable inorganic ETL for realizing high-performance Sn-Pb PSC and its tandem applications.

For perovskite/silicon tandem solar cells (TSCs), optical losses remain a critical factor limiting their efficiency improvement. Although pyramid-textured structures have been widely introduced into perovskite/silicon TSCs to reduce optical losses, how to fully unlock their optical performance and clarify their design principles and mechanisms remains unclear. Herein, we conduct a systematic opto-electrical simulation to elucidate the physical mechanisms underlying pyramid-textured structures and explore their potential for high-efficiency perovskite/silicon TSCs. Optical simulation results reveal that large micrometer-scale textures on both sides of the perovskite layer are necessary, as they not only enhance the optical response in the top perovskite sub-cell but also exhibit greater robustness to variations in perovskite thickness and bandgap, thereby facilitating photocurrent (Jph) matching and higher Jph output. Moreover, we also confirm that non-uniform perovskite morphology significantly degrades the optical performance of TSCs, requiring an increase in perovskite thickness to mitigate this effect. Through combined optimization, including the introduction of a rear-side dielectric layersilver grid structure, adjustment of the thicknesses of the front-side transparent conductive film, electron transport layer, and anti-reflection layer, as well as Jph matching, a high Jph of 21.17 mA/cm2 is achieved for perovskite/c-Si TSCs. Further electrical simulations show that textured perovskite morphology is crucial for TSCs to achieve high efficiency, except in cases where the electrical properties of the perovskite are relatively poor. This work provides a reference for designing perovskite/silicon TSCs with textured structures.

Perovskite-based solar cells are widely recognized as one of the most promising next-generation photovoltaic technologies. However, the selection and optimization of charge transport layer materials remain challenging, particularly for all-perovskite tandem solar cells (TSCs), which involve more complex multi-interface coupling and interactions. In this work, we propose a rigorous optoelectronic coupling model that integrates machine learning techniques to identify key transport layer parameters affecting the performance of all-perovskite TSCs, thereby guiding material selection and device optimization strategies. Numerical simulations reveal that both wide-bandgap and narrow-bandgap perovskite subcells achieve high performance and exhibit strong tolerance to interface defects when a well-matched energy band alignment is realized using wide-bandgap hole and electron transport layers (HTL/ETL). SHAP analysis further indicates that the valence/conduction band offset is the key efficiency-determining factor, with an almost aligned valence band at the perovskite/HTL interface being optimal for hole extraction. Strategic doping can also modulate the interfacial electric field to mitigate the negative effects of suboptimal band alignment. By optimizing the optical and electrical properties of ETL and HTL materials and incorporating an interfacial buffer layer, we propose a feasible pathway toward achieving 33% efficiency in both n-i-p and p-i-n structured all-perovskite TSCs.

All-perovskite tandem solar cells (TSCs) offer a path to exceed the Shockley-Queisser limit of single-junction devices, yet their development is hindered by the inferior efficiency and stability of low-bandgap tin-lead (Sn-Pb) perovskite bottom cells. The inherent grain boundaries (GBs) in Sn-Pb perovskites feature detrimental p-type energy states and unfavorable upward energy band bending that promote non-radiative charge recombination and pathways for ion migration-induced degradation. Herein, we employ dipole management at GBs of Sn-Pb perovskite by 4-(trifluoromethyl)benzohydrazide (FBH), which effectively modulates the GB energy landscape throughout the film. The dipole effect reverses the top surface GB energy states to create downward bending of the energy band, promoting efficient charge separation at GBs. Concurrently, FBH treatment enhances perovskite film quality through grain growth regulation, defect passivation, and immobilization of FA+/I- ions. Consequently, the optimized Sn-Pb perovskite solar cell achieves a high efficiency of 23.25% with outstanding operation stability, i.e., keeping over 80% of its initial efficiency under 85°C thermal stress after 400 h and 90% of its original efficiency upon 1872 h in glove box. All-perovskite TSC obtains 29.67% efficiency and retains 90% of its initial efficiency after approximately 1000 h maximum power point tracking.

Perovskite/silicon tandem solar cells (PSTSCs) face a significant challenge in achieving uniform deposition of a self-assembled monolayer (SAM) on industrial-scale microtextured silicon substrates. In particular, nonuniform SAM coverage not only hinders the formation of high-quality perovskite films but also introduces additional interfacial defects and leads to further stress accumulation, thereby degrading device efficiency and stability. However, the underlying mechanisms behind nonuniform SAM coverage remain unclear. Here, we develop a comprehensive optoelectrothermal coupled simulation model to systematically investigate the optoelectronic coupling, carrier-ion dynamics, thermal-stress behavior, and corresponding mitigation strategies of nonuniform SAM-based PSTSCs. The simulation results reveal that nonuniform SAM coverage leads to inhomogeneous carrier transport and significantly increases carrier recombination in SAM-uncovered regions, particularly at the pyramid peaks, resulting in severe performance degradation. Additionally, nonuniform SAM coverage exhibits low tolerance to variations in perovskite film quality, interfacial passivation, reverse breakdown, and ion migration behavior. Moreover, residual stress induced by thermal mismatch shows a clear morphology dependence, with nonuniform SAM coverage leading to localized stress accumulation. Despite these adverse effects, we find that the performance degradation caused by nonuniform SAM coverage can be mitigated by increasing the photocurrent in the perovskite top cell, offering insights into designing high-efficiency and stable PSTSCs.

Perovskite/silicon tandem solar cells (PSTSCs) suffer from nonconformal perovskite coverage on industrial-grade micron-textured silicon, leading to efficiency and stability degradation. This study combines photoelectrical simulations and experiments to elucidate the degradation mechanisms and develop mitigation strategies. It reveals that conformal deposition improves optical response and reduces electrical losses. Beyond perovskite morphology regulation, increasing the perovskite subcell current can further alleviate performance degradation. To validate simulation results, we fabricate PSTSCs with varying perovskite morphologies and thicknesses, achieving precise current matching and enhanced performance. Notably, the optimized PSTSCs, featuring thick and conformal perovskites, achieve an efficiency beyond 32% (∼1 cm2) with hysteresis (<1%) and enhanced long-term stability, retaining 98% of their initial efficiency after 430 h of continuous maximum power point tracking. These findings not only advance the understanding of textured PSTSCs but also provide practical insights for enhancing their efficiency and stability, thereby facilitating the commercial development of PSTSCs.

As a promising photovoltaic technology, perovskite solar cells and tandems face the critical challenge of reverse-bias breakdown stability, which significantly hinders their commercialization. However, the fundamental mechanisms behind reverse-bias breakdown remain poorly understood. To address this, the underlying mechanisms of reverse-bias breakdown are systematically elucidated and targeted optimization strategies are proposed through a synergistic approach combining photoelectrical coupled simulations with well-designed experiments. Notably, it is identified that the reverse-bias breakdown is primarily governed by Zener tunneling, triggered by localized electric field amplification at the perovskite interfaces. Furthermore, misaligned energy band structures and ion migration further accelerate Zener breakdown and reduce the breakdown voltage. The pronounced ion accumulation of ion migration over extended operational periods also induces progressive degradation of device performance under fixed reverse bias over time. Additionally, narrow-bandgap perovskite cells exhibit significantly higher breakdown voltages but lower robustness than wide-bandgap perovskite cells, resulting in the breakdown characteristics of tandem cells being dominated by the narrow-bandgap perovskite sub-cells. These findings provide a solid theoretical basis for the design and industrialization of efficient and stable perovskite photovoltaics.

All-perovskite tandem solar cells (TSCs) have attracted extensive interest owing to their tunable bandgaps, low cost, and excellent optoelectronic properties. Nevertheless, the efficiency of all-perovskite TSCs remains substantially below the theoretical limit, largely attributable to the lack of textured structures, which results in considerable reflection losses. In this work, we carry out rigorous optoelectronic coupled simulations on allperovskite TSCs incorporating four periodic pyramid textured structures, aiming to develop a deeper understanding of their device operational mechanisms and photovoltaic optimization strategies. Through detailed optical simulations, we demonstrate that a front-side textured structure with a relatively small feature size markedly improves the optical performance of TSCs, particularly in the short-wavelength range, thereby enhancing the wide-bandgap sub-cell. The middle-layer textured structure has the least influence on the optical performance and exerts a weak effect on the overall optoelectronic performance of the TSC, with a fluctuation in the photocurrent current density of less than 0.5 mA/cm2. A rear-side textured structure with a relatively larger feature size predominantly boosts light-trapping in the long-wavelength range, thus mainly benefiting the narrow-bandgap perovskite sub-cell. The overall optical improvement across all textured structures can be ascribed to reduced reflection losses. Electrical simulations reveal that variations in TSC efficiency are primarily governed by optical properties. Moreover, all-perovskite TSCs with fully textured structures achieve a high photocurrent density of 17.59 mA/cm2 through current-matching optimization and a reflection loss as low as 3.60 mA/cm2. This study offers meaningful direction for the design of textured all-perovskite TSCs with superior optoelectronic performance.

Large-area perovskite light-emitting diodes (LEDs) remain limited by severe performance losses arising from grain boundary defects and nonuniform film formation. Here we introduce a ZnBr2-mediated crystallization strategy that selectively passivates grain boundary defects while inducing the in situ formation of the wide-bandgap Cs2ZnBr4 interphase. This intergranular phase bridges adjacent CsPbBr3 grains, suppressing trap-assisted recombination, directing preferential crystal orientation, and enhancing environmental stability. Leveraging this approach, we realize large-area quasi-2D perovskite LEDs (active area: 225 mm2) exhibiting record-high external quantum efficiencies (EQEs) of 25.2% for green emission at 516 nm and 23.7% for red emission at 640 nm, which are the highest reported to date for devices of this scale. These results establish intergranular phase engineering as an effective and generalizable route to overcome intrinsic scaling challenges in quasi-2D perovskites, paving the way for efficient, stable, and manufacturable perovskite light-emitting technologies.

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.

All-perovskite tandem solar cells (TSCs) demonstrate exceptional potential to overcome the single-junction efficiency limit through enhanced photon harvesting across the solar spectrum and suppressed thermalization effects, achieving theoretical power conversion efficiencies surpassing 44%. Wide-bandgap perovskites solar cells (WBG PSCs) are crucial for tandem photovoltaics, and have witnessed exponential progress during the last decade. However, these devices suffer from severe open-circuit voltage (VOC) deficits, primarily due to interfacial recombination and carrier transport losses. A major contributor to these losses is the uncontrolled formation of insulating two-dimensional (2D) perovskite phases during surface passivation. Here, we introduce 4-hydroxyphenylethyl ammonium iodide (p-OHPEAI) as a multifunctional molecular additive to address this critical trade-off. Unlike conventional phenethyl ammonium iodide (PEAI), which forms the insulating 2D phase and the invert electric field by vertical molecular orientation that impedes charge extraction, the hydroxyl group (-OH) in pOHPEAI enables parallel molecular adsorption on perovskite surfaces via synergistic interactions between amino (-NH3) and -OH groups. This configuration effectively eliminates the formation of insulating 2D perovskite phase, passivates undercoordinated halide and lead vacancies, reducing non-radiative recombination. Additionally, the polarity of p-OHPEAI generates a dipole moment at the perovskite/electron transport layer (ETL) interface, optimizing energy-level alignment and facilitating electron extraction. By incorporating p-OHPEAI into 1.77 eV WBG PSCs, we achieved a remarkable VOC of 1.344 V, corresponding to a minimal voltage deficit of 0.426 V, which is among the lowest reported VOC-deficit values for the inverted WBG PSCs with bandgaps ranging from 1.75 to 1.80 eV. The optimized device delivered a power conversion efficiency (PCE) of 19.24%, demonstrating superior performance compared to conventional PEAI-passivated cells. When integrated into all-perovskite TSCs, this strategy enabled a champion PCE of 28.50% (with a certified efficiency of 28.19%). Furthermore, the devices exhibited excellent operational stability, maintaining over 90% of their initial efficiency after 350 h of continuous illumination, highlighting the robustness of the hydroxyl-driven passivation approach. The introduction of hydroxyl groups in passivation molecules provides a versatile strategy to balance defect suppression and charge transport, bridging the gap between high voltage and efficient carrier extraction.

All-perovskite tandem solar cells (APTSCs) have rapidly improved in both power conversion efficiency (PCE) and room-temperature stability. However, achieving device stability under combined light-heat stresses (ISOS-L-3 conditions) remains challenging. The critical limitation stems from the highly reactive tin-lead surface which, even with molecular passivation strategies, remains susceptible to severe photothermal degradation. Here we develop a targeted conversion strategy to transform the metastable surface into a solid protection layer. Our method relies on treatment with alkaline caesium hydroxide, which releases OH- to mediate the dual transformation of SnI4 and the defective surface into solid metal oxides, as well as replacing volatile organic cations with Cs+. This strategy leads to improved stability under ISOS-L-3 testing conditions and overall optoelectronic performance. The resulting tin-lead cells achieve a champion PCE of 23.65%, enabling the corresponding APTSCs to reach a PCE of 29.52% (certified, 28.56%). The APTSCs retain 90.3% of their initial PCE after 500 h under ISOS-L-3 conditions, outperforming traditional amine-treated counterparts. Our findings demonstrate a promising pathway towards photothermally stable and efficient APTSCs.

Wide-bandgap (WBG) perovskites have emerged as promising materials for all-perovskite tandem solar cells (ATSCs) for their potential to surpass the Shockley-Queisser limit of single-junction perovskite solar cells (PSCs). However, nonradiative recombination at the buried interface of WBG PSCs remains a great challenge, limiting the efficient carrier transport and collection in these devices. Hole selecting materials (HSMs) play a crucial role in charge extraction and growth of the overlying perovskite films. Here, we systematically investigated the deposition of various self-assembled monolayer (SAM) materials on NiO x to modify the NiO x /perovskite interface. A sequential deposition of (4-(7H-dibenzo[c,g]-carbazol-7-yl)butyl)phosphonic acid (4PADCB) and [4-(3,6-diphenyl-9H-carbazol-9-yl)butyl]phosphonic acid (Ph-4PACz) is found to result in optimized efficiency, which can be attributed to the ability of sequential deposition to fill the gaps and form a more compact and uniform buried interfacial contact compared to coating each layer separately. Moreover, the modified buried interface notably eliminates the formation of the small grains, which may be caused by random nucleation. This strategy also enhances energy level alignment, decreasing the barrier for carrier transport at the buried interface. As a result, the champion single-junction WBG PSC achieves an open-circuit voltage (V OC ) of 1.33 V and an efficiency of 20.35%. The ATSCs fabricated with the WBG subcells based on the reported strategy achieve an optimized efficiency of 27.03%, exhibiting the great potential of the sequential deposition method for SAMs on future perovskite photovoltaics.

Mobile ions, widely present in perovskite devices, play a pivotal role not only in modulating carrier dynamics but also in facilitating electrochemical reactions, ultimately compromising device efficiency and operational stability. However, the intricate multi-physical mechanisms governing carrier-ion interactions and multi-particle-coupled electrochemical reactions pose substantial challenges to improving device performance. This is particularly relevant for perovskite/silicon tandem solar cells (TSCs), which feature complex multilayer architectures and intricate interfacial interactions. In this study, a self-consistently coupled multi-physics simulation model for perovskite/silicon TSCs is developed that integrates carrier transport, ion migration, and electrochemical reactions, with the aim of elucidating the fundamental mechanisms underlying carrier-ion interactions and proposing viable optimization strategies. The simulations reveal that ionic reactions significantly influence carrier and ion distributions, potentially inducing energy losses that degrade device performance, while also partially compensating for efficiency degradation arising from energy-band misalignment. Specifically, cations exhibit a pronounced tendency to react with electrons under reverse bias scanning, leading to substantial reaction-induced losses and severe performance degradation, whereas anions demonstrate stronger reactivity with holes under forward bias scanning. This work provides fundamental insights into the carrier-ion-electrochemical interplay in perovskite/silicon TSCs, thereby offering valuable guidance for the development of high-efficiency and stable perovskite-based devices.

This study successfully applies scanning capacitance microscopy (SCM) to organic-inorganic metal halide perovskite materials, providing detailed insights into the microscopic distribution of carrier concentrations and types. We developed and optimized an alumina (Al2O3) insulating layer using atomic layer deposition, with a 5 nm thickness at 398.15 K proving optimal for minimizing defects at the Al2O3/perovskite interface. Further optimizations included selecting an appropriate probe for high-contrast SCM imaging, reducing stray capacitance by scanning at sample edges, and analyzing the effects of light illumination. Our results show that perovskite films with excess PbI2 in the precursor had a more uniform carrier distribution and higher overall carrier concentration. Additionally, we identified distinct p-type and n-type regions in perovskite materials modified with polar molecular additives. This work enables SCM as a robust technique for investigating complex carrier behaviors in perovskite materials.