The incorporation of the Se element in CdTe solar cells is critical, while the low bandgap CdSexTe1-x, formed by the interdiffusion of CdTe and CdSe during device preparation, can promote the carrier lifetime. Different window layers formed by CdSe w/o MZO or CdS have different Se distributions. This paper systematically evaluates the influence of four types of window layers (CdSe, CdS/CdSe, MZO/CdSe and MZO/CdS/CdSe) on the performance of CdTe solar cells, and focuses on the correlation between the window layers and the Se distribution characteristic, carrier recombination mechanism, and device efficiency. The results show that CdSe and MZO/CdS/CdSe window layer devices achieve Eff of 15.21% and 14.40%, respectively. The CdSe and MZO/CdS/CdSe devices exhibit relatively high Ea of 1.41 eV and 1.39 eV from J-V-T measurements, coupled with high Rrec of 9458 Q and 8293 Q, respectively. This indicates suppressed recombination, suggesting that non-radiative recombination is reduced. In contrast, the CdS/CdSe and MZO/CdSe devices show lower performance. Their extrapolated Ea values are 1.25 eV and 1.31 eV, with correspondingly lower Rrec values of 2207 Q and 3304 Q. These results point to faster recombination rates and an increased proportion of non-radiative recombination, consistent with their suboptimal Eff. Detailed analysis of Se distribution reveals that S-Se interdiffusion in S-containing devices results in the x-value decrease (highest value of Se content in CdSexTe1-x), thereby suppressing the long-wavelength expansion. In devices of S-free window layers, the formed CdSexTe1-x alloy has a relatively higher x-value, allowing the long-wavelength response to extend beyond 850 nm. It can be concluded that CdSe is the optimal window layer for CdTe Solar Cells, which can both form a desirable Se distribution and a good junction with less interface recombination.

A crown ether named dibenzo-18-crown-6 is introduced to modify the interface between the perovskite and the electron transport layers. Due to its unique electron cavity and electron-rich system, it effectively passivates defects and simultaneously suppresses cation migration, thereby achieving a high power conversion efficiency of 24.19% with excellent stability.

Tunnel Oxide-Passivated Back Contact solar cells represent a next-generation photovoltaic technology with significant potential for achieving both high efficiency and low cost. This study addresses the challenge of low bifaciality inherent to the rear-side structure of TBC cells. Using the Quokka3 simulation and assuming high-quality surface passivation and fine-line printing accuracy, a systematic optimization was conducted. The optimization encompassed surface morphology, optical coatings, bulk material parameters (carrier lifetime and resistivity), and rear-side geometry (emitter fraction, metallization pattern and gap width). Through a multi-parameter co-optimization process aimed at enhancing conversion efficiency, a simulated conversion efficiency of 27.26% and a bifaciality ratio of 92.96% were achieved. The simulation analysis quantified the trade-off relationships between FF, bifaciality, and efficiency under different parameter combinations. This enables accurate prediction of final performance outcomes when prioritizing different metrics, thereby providing scientific decision-making support for addressing the core design challenges in the industrialization of TBC cells.

Self-assembled monolayers (SAMs) as hole-selective contacts have driven the power conversion efficiencies (PCEs) of inverted perovskite solar cells (IPSCs) beyond 27%, yet their poor operational stability remains a major barrier to commercialization. We report that strengthening the spatial confinement of SAMs through robust out-of-plane anchoring and dense in-plane packing can effectively suppress molecular desorption and enhance thermal and solvent resistance. A custom-designed molecule, MeO-PABDCB, forms strong bonds with both the underlying indium tin oxide (ITO) and the overlying perovskite, while its rigid, planar backbone promotes tight π-π stacking (3.72 Å). This multi-dimensionally confined SAM structure not only resists solvent washing and thermal degradation but also mitigates interfacial strain in the perovskite layer, facilitating highly efficient and stable hole extraction. The resulting IPSCs achieve a champion PCE of 26.54% with a fill factor of 86.4% and retain 90% of their initial efficiency after 1000 h of maximum power point tracking (ISOS-L-1). Devices also withstand 250 harsh thermal cycles between -40 and 85 °C (IEC61215 and ISOS-T-3) while preserving over 90% of their initial performance. This work establishes spatial confinement as a general molecular design principle toward durable and high-performance perovskite optoelectronics.

Non-radiative energy loss remains a critical bottleneck limiting the open-circuit voltage (VOC) and efficiency of organic solar cells (OSCs). Here, we introduce a molecular design strategy that leverages aggregation-induced emission (AIE) to suppress aggregation-caused quenching and enhance solid-state photoluminescence quantum yield (PLQY), thereby mitigating non-radiative recombination. A prototypical AIE motif, tetraphenylethylene, was incorporated into the terminal group of a Y-series non-fullerene acceptor to yield dTPE, which exhibits distinct AIE characteristics not previously observed in high-performance Y-series acceptors. Photoluminescence studies reveal that dTPE achieves a threefold enhancement in PLQY compared to L8BO-C4 in the film, leading to an electroluminescence external quantum efficiency more than an order of magnitude higher than that of D18:L8BO-C4. Consequently, the binary D18:dTPE device achieves a remarkably low non-radiative recombination loss of 0.130 eV. When incorporated as a guest into D18:L8BO-C4 blends, dTPE enables a non-radiative voltage loss of only 0.190 eV and an unprecedented VOC of 0.93 V, yielding an efficiency of 20.5%. To our knowledge, this represents the highest VOC reported for OSCs with efficiencies above 20%. This work establishes AIE molecular design as an effective pathway to overcome intrinsic limitations of Y-series acceptors and provides guiding principles for mitigating non-radiative energy loss in next-generation OSCs.

The bis-phosphonic acid groups of 1,4-phenylenebis(phosphonic acid) passivate defects at the buried interface, enabling 1.66 eV WBG PSCs with a high V oc of 1.195 V, 21.79% efficiency, and enhanced stability.

Although metallic aluminum (Al) is an attractive back electrode material for cadmium telluride (CdTe) solar cells due to its low cost and suitability for large-area deposition, its low work function has hindered widespread application. To overcome this challenge, we designed and implemented a molybdenum-chromium (Mo/Cr) interfacial modification layer. A comprehensive comparative analysis was carried out to evaluate the electrical characteristics, interfacial transport properties, and device performance of the Al, Mo/Cr-modified Al and Au electrodes. The results reveal that the Mo/Cr interfacial modification layer effectively improves Al-electrode interfacial transport properties and conductivity and also blocks the diffusion of Al atoms. The optimized device with a Mo/Cr-modified Al electrode achieved a champion efficiency of 15.68%, closely approaching 15.88% of the expensive, high-work-function gold (Au) reference and significantly surpassing 13.83% of the Al electrode. Furthermore, it exhibited excellent mechanical adhesion and wear resistance, with a critical load of 0.62 mN, substantially higher than the 0.45 and 0.42 mN for the Al and Au electrodes, respectively. This electrode architecture offers a low-cost, highly durable, and high-performance alternative to noble-metal contacts, showing great potential for facilitating the large-scale commercialization of thin-film photovoltaic technology.

Introducing a 2D perovskite layer on the surface of 3D perovskite has been broadly recognized as an effective strategy to enhance the performance of perovskite solar cells (PSCs). However, the mechanism governing the 2D phase formation remains uncertain. In this work, the phase transitions of 2D perovskite during spin-coating and annealing processes has been investigated. Our findings reveal a dimensional phase shift from low to high n-value 2D phases, driven by the release of organic cations during annealing. Additionally, the spin-coating process exhibited concentration-dependent behavior, where higher n-octylamine hydrobromide (OABr) concentrations predominantly formed n = 1 phases. These observations highlight the complexity of the 2D phase composition at the 2D/3D interface. The coexistence of various 2D phases significantly influences device performance, as a conflict between n = 1 and n ≥ 2 phases was identified. Through forming a well-balanced proportion of different 2D phases, we achieved a wide-bandgap perovskite solar cell with a significantly improved power conversion efficiency of 19.29%. This work suggests the critical roles of phase dynamics and n-value distribution in optimizing 2D/3D interfaces for advancing high-performance wide-bandgap PSCs.

Doping the absorber layer is a critical process for enhancing the performance of polycrystalline CdSeTe solar cells. Replacing traditional Cu doping with Group V dopants offers a pathway to fabricate devices with improved efficiency and stability. However, the dopant activation rate in polycrystalline structures remains low, typically only a few percent. While rapid thermal annealing (RTA) has been successfully employed to achieve high activation rates in single-crystal CdTe devices, its application to polycrystalline CdSeTe solar cells has been scarcely reported. In this study, we systematically applied multi-step annealing to investigate the dopant activation of in-situ As-doped polycrystalline CdSeTe devices. Our findings reveal that polycrystalline devices exhibit significantly lower thermal tolerance than their single-crystal counterparts, sustaining only short-duration annealing at 500 degrees C. Furthermore, although Cl diffusion during RTA can degrade device performance, we observed that trace amounts of CdCl2 vapor can help stabilize device efficiency.

A small-molecule acceptor, S-Cb, substituted with a cyclobutyl group that introduces high ring strain, was designed and synthesized. Thanks to the rigid and planar structure of cyclobutyl, S-Cb can form interchain supramolecular interactions through hydrogen bonding with L8-BO at the external side chains. This clamping effect not only effectively suppresses the electron-phonon coupling but also promotes the formation of high-quality acceptor alloy phases in the ternary active layer, thereby optimizing carrier behaviors and reducing non-radiative energy loss. The clamping effect reaches its maximum when S-Cb and L8-BO are in equal proportion, where organic solar cells (OSCs) based on D18:S-Cb:L8-BO achieved an impressive efficiency of 20.93%, with a certified efficiency of 20.74%. In summary, the cyclobutyl-mediated interchain supramolecular interactions suppress the electron-phonon coupling and optimize the acceptor alloy phase for efficient ternary OSCs.

Enhancing the efficiency and stability of perovskite solar cells is critical for commercialization. As short-circuit density approaches the Shockley-Queisser limit, improving open-circuit voltage and fill factor becomes essential, achievable through interface engineering. SnO2, employed as a buried electron transport layer, not only influences the deposition of perovskite film but also poses significant stability. Here, we introduce a multifunctional amphiphilic molecule, hydroxyl-terminated perfluoroalkyl sulfonamide, into the buried interface. The C-F long chain facilitates hydroxyl groups anchoring on the SnO2 surface, while the sulfonyl groups occupy oxygen vacancies, thereby reducing undercoordinated Sn4+. Simultaneously, the sulfonyl groups interact with uncoordinated Pb2+ in the adjacent perovskite film, further suppressing interfacial defects. This strategy yields a champion power conversion efficiency of 23.26%. Moreover, the long C-F chains act as a hydrophobic barrier against moisture ingress, enabling the unencapsulated devices to retain 73.8% of initial PCE after 1320 h under ambient condition (50%-60% relative humidity), while only 69.4% for reference one. Furthermore, posttreatment with quaternary ammonium iodide creates a dual-passivated interface. This suppresses halide ion migration and photoinduced phase segregation, boosting the PCE to 24.64%. These results underscore the critical role of multifunctional organic molecular passivation at interface in achieving both high-performance and durable perovskite photovoltaics.

Back surface engineering is one of the ways to further improve the conversion efficiency of the CdTe solar cells. In this work, as an oxide mixture, Cu x In y O is synthesized by low-temperature solution processing and successfully applied to the CdTe solar cells in the form of amorphous nanoparticles. The XPS results reveal changes in the chemical states of Te and O, and the KPFM demonstrate that a similar to 350 mV electric field has been introduced at the CdTe back surface, which means effective chemical passivation and field passivation were induced, resulting in the suppression of carrier recombination and the increase of carrier lifetime at the back interface of the devices. Finally, compared to the control devices, the conversion efficiency of the devices with Cu x In y O buffer layer improved from 12.44% to 15.35%, attributed to the increase in the fill factor from 65.52% to 72.48% and the open-circuit voltage from 723 mV to 798 mV.

Abstract Against the global demand for renewable and sustainable clean energy, perovskite solar cells (PSCs) have shown great potential as a next-generation photovoltaic technology, owing to their high photoelectric conversion efficiency (PCE) and low-cost potential. Although the highest PCE of PSCs has exceeded 27%, poor stability and severe nonradiative recombination loss still hinder their further development. PSCs contain several critical interfaces, including the electron transport layer (ETL)/perovskite, hole transport layer (HTL)/perovskite, and charge transport layer (CTL)/electrode, which strongly influence carrier dynamics and dominate device efficiency and stability. Interface engineering has attracted extensive attention as an effective modification strategy, yet a systematic review focusing on its working mechanism is insufficient. In this review, we analyze the influence of interfacial defects on carrier dynamic processes and comprehensively summarize the latest progress of interface engineering in PSCs from ETL/perovskite, HTL/perovskite, and CTL/electrode aspects. We highlight the key roles of interface engineering in rationalizing energy-level alignment, passivating defects, optimizing perovskite film quality, and improving device stability. We also provide general guidance for selecting appropriate interfacial strategies according to specific performance bottlenecks. Finally, the challenges and future perspectives of interface engineering toward high-performance PSCs are discussed.

Wide-bandgap perovskite solar cells are crucial for realizing efficient tandem solar cells. However, their efficiency and stability are severely constrained by the limitations of common hole-transport materials. Conventional hole-transport materials like nickel oxide (NiOX) suffer from high surface defect density and poor conductivity, while self-assembled monolayers (SAMs) are plagued by intrinsic shortcomings in structural and long-term stability. Herein, we propose a bilayer hole-selective contact composed of NiOX and a 9H,9'H-[3,3'-bicarbazole]-9,9'-diylbis(butane-4,1-diyl) diphosphonic acid (DCZ) SAM molecule, which facilitates hole extraction and improves perovskite crystallization. Consequently, the champion device with a 1.77 eV perovskite achieves a PCE of 19.24% and an open-circuit voltage of 1.31 V, retaining 80% of its initial efficiency after 380 h of continuous illumination at maximum power point tracking. Furthermore, this approach could be extended to perovskite systems with bandgaps of 1.68 and 1.58 eV, delivering impressive PCEs of 22.92 and 24.93%, respectively.

The hole-transport layer (HTL) plays a pivotal role in engineering high-performance inverted perovskite solar cells (PSCs), as it governs both hole extraction/transport dynamics and critically impacts the crystallization quality of the perovskite absorber layer in device architectures. Recent advancements have highlighted self-assembled monolayers (SAMs) as promising candidates for next-generation HTL materials in inverted PSCs due to their intrinsic advantages over conventional counterparts. These molecularly engineered interfaces demonstrate superior characteristics including simplified purification processes, tunable molecular structures, and enhanced interfacial compatibility with device substrates. This review systematically examines the progress, existing challenges, and future prospects of SAM-based HTLs in inverted photovoltaic systems, aiming to establish a systematic framework for understanding their structure–property relationships. The review is organized into three sections: (1) fundamental architecture of inverted PSCs, (2) molecular design principles of SAMs with emphasis on head-group functionality, and (3) recent breakthroughs in SAM-engineered HTLs and their modification strategies for HTL optimization. Through critical analysis of performance benchmarks and interfacial engineering approaches, we elucidate both the technological merits and inherent limitations of SAM implementation in photovoltaic devices. Furthermore, we propose strategic directions for advancing SAM-based HTL development, focusing on molecular customization and interfacial engineering to achieve device efficiency and stability targets. This comprehensive work aims to establish a knowledge platform for accelerating the rational design of SAM-modified interfaces in next-generation optoelectronic devices.

The primary challenge in commercializing perovskite solar cells (PSCs) mainly stems from fragile and moisture-sensitive nature of halide perovskite materials. In this study, we propose an asynchronous cross-linking strategy. A multifunctional cross-linking initiator, divinyl sulfone (DVS), is firstly pre-embedded into perovskite precursor solutions. DVS, also as a special co-solvent, facilitates intermediate-dominated perovskite crystallization manipulation, favouring formamidine-DVS based solvate transition. Subsequently, DVS-embedded perovskite as-cast films are post-treated with a nucleophilic reagent, glycerinum, to trigger controllably three-dimensional co-polymerization. The resulting cross-linking scaffold provides enhanced water-resistance, releases residual tensile strain, and suppresses deep-level defects. We achieve a maximum efficiency over 25% (certified 24.6%) and a maximum VOC of 1.229 V, corresponding to mere 0.30 V deficit, reaching 97.5% of the theoretical limit, which is the highest reported in all perovskite systems. This strategy is generally applicable with enhanced efficiencies approaching 26%. All-around protection significantly improves PSC's operational longevity and thermal endurance. The primary challenge in commercializing perovskite solar cells stems from the fragile and moisture-sensitive nature of perovskite materials. Here, authors propose a multi-functional asynchronous cross-linking strategy and achieve high-performance and stable devices with mere 0.30 voltage deficit.

In organic solar cells (OSCs), the ternary strategy is a mainstream approach to obtaining highly efficient OSCs. A deeper understanding of working mechanisms and the material selection criteria for boosting open-circuit voltage (VOC) is essential for further OSC breakthrough. Through a modular design principle, a series of oligomeric donors - 5BDD, 5BDD-F, 5BDT-F, and 5BDT-Cl - with similar molecular configurations but varying HOMO levels is systematically designed. These findings reveal that the HOMO levels of these oligomers have a negligible impact on the VOC of the ternary OSCs. Instead, their excellent compatibility with acceptors played a pivotal role in enhancing VOC. The oligomers effectively suppressed excessive acceptor aggregation and achieved Aggregation-Caused Quenching Suppression (ACQS), strengthening the external electroluminescence quantum efficiency (EQEEL) and reducing non-radiative recombination energy losses. Simultaneously, oligomers fine-tuned and optimized the morphology of the blend films, leading to a higher fill factor (FF) and improved performance. Notably, the 5BDT-F- and 5BDT-Cl-based ternary OSCs achieved impressive power conversion efficiencies (PCEs) of 19.8% and 20.1% (certified 19.76%), with FFs of 80.9% and 80.7%, respectively. This work elucidates the unusual role of the third component energy levels on the VOC in ternary OSCs and offers valuable guidance for future OSC design.

Wide-bandgap (WBG) perovskite solar cells (PSCs, Eg > 1.6 eV), serving as the top cell in perovskite/silicon tandem solar cells (PSTSCs), play an indispensable role in absorbing high energy photons and increasing overall efficiency. However, WBG PSCs often suffer from severe light-induced phase segregation and significant non-radiative recombination losses due to uncontrolled rapid crystallization. Here, polyfluoride molecular additives are designed and incorporated via (diacetoxyiodo)benzene into WBG perovskite, to regulate crystallization process of perovskite films and thereby reduce defects. (Bis(trifluoroacetoxy)iodo)benzene (BTFIB) can passivate uncoordinated lead ions and iodide vacancies, thereby inhibiting phase separation caused by iodide migration and reducing non-radiative recombination loss during charge transport. Moreover, the introduction of BTFIB can effectively moderate the film formation process and confer excellent hydrophobic properties to the films. Consequently, BTFIB-based 1.67 eV-WBG perovskite devices yield a champion efficiency of 23.05% (certified efficiency of 22.21%), enabling a 31.20% efficiency in four-terminal PSTSCs, along with excellent open-circuit voltage of 1.246 V and fill factor of 85.34%. After 2500 h of aging in a glovebox, the device retained 80% of its initial efficiency.

Blade coating is a promising tool for upscaling organic solar cells (OSCs). However, the performances of blade-coated OSCs still lag behind their spin-coated counterparts, limiting their competitive edge towards commercialization. One of the main reasons is that controlling the film aggregation kinetics and morphology becomes challenging during the transition from spin coating to blade coating, especially when using high boiling point solvents, which can result in excessive aggregation. Therefore, a deeper understanding and appraisal of film formation kinetics influenced by coating methods is crucial. In this work, it is demonstrated that ink solubility tuning by incorporating a twisted third component (BTP-4Cl) can induce rapid crystallization behavior and promote fine phase separation between the donor polymer (PM6) and the acceptor (BTP-eC9) in blade coating. As a result, a high power conversion efficiency (PCE) of 19.67% is obtained in OSCs (0.04 cm2), one of the state-of-the-art efficiencies among the reported blade-coated OSCs (19.76% for the spin-coated devices). In addition, it is found that the inhibited phase aggregation contributes to enhancing the light stability of the device. This strategy offered novel insights into the effectiveness of solubility-tuning approaches for achieving highly efficient and stable OSCs under open-air coating conditions.