Chen Weijie

It is introduced 1,3-dibromo-5-iodobenzene (DBI) as a volatile solid additive with multiple noncovalent interactions to concurrently optimize both donor and acceptor phases. As validated by PM6:L8-BO:L8-BO-F ternary system, adding an optimal amount of DBI achieves a champion power conversion efficiency of 20.6% with a boosted operational stability (T80:769 h) under continuous light-soaking condition.

Abstract

Immense trap densities arising from faint donor self-assembly and excessive acceptor aggregation severely restrain power conversion efficiencies (PCEs) in organic solar cells. Yet, most studies focus solely on acceptor regulation, and synergistic co-modulation of donor and acceptor phases for trap suppression has rarely been achieved. Here, 1,3-dibromo-5-iodobenzene (DBI) as a volatile solid additive with multiple noncovalent interactions to concurrently optimize both phases is introduced. Using PM6:Y6 as representative, from systemic coarse-grained molecular dynamic simulation, in-situ synchronic and spectroscopy and transient optoelectronic characterizations, it is demonstrated that DBI can selectively bind with the fluorinated benzo[1,2-b:4,5-b′]dithiophene segments in PM6 backbone, which strengthens interchain interactions, enhances interchain packing density, and triggers the pre-aggregation of PM6 in solution state. Moreover, this preferentially precipitation of PM6 matrix sterically mitigates the oversized Y6 aggregation, which yields well-defined phase separation with appropriate domain sizes, which markedly substitute energetic disorder and trap density. As a result, the DBI treated devices yielded an elevated performance of 18.4% compared to 17.0% for reference devices. The generality of such strategy is also validated by PM6:L8-BO:L8-BO-F ternary system, where adding an optimal amount of DBI achieves a champion PCE of 20.6% with a boosted operational stability (T₈₀:769 h) under continuous light-soaking condition.

A new conjugated catechol-anchored self-assembled monolayer (9-(3,4-dihydroxyphenyl)-9H-carbazole, DOPhCz) is designed to enhance molecular packing, reduce interfacial defects, and improve charge extraction, enabling highly efficient and stable Sn─Pb and all-perovskite tandem solar cells with power conversion efficiencies of 24.17% and 28.30%, respectively.

ABSTRACT

The performance of all-perovskite tandem solar cells is strongly dependent on the properties of Sn-Pb narrow-bandgap subcells. Self-assembled monolayers (SAMs) such as 2PACz have shown great success in lead-based perovskite solar cells (PSCs), yet their application in Sn─Pb PSCs remains limited, largely due to suboptimal carrier-extraction capability and insufficient interfacial stability. Here, we design and introduce a new SAM, 9-(3,4-dihydroxyphenyl)-9H-carbazole (DOPhCz), featuring a conjugated catechol anchoring group, into Sn─Pb PSCs for the first time. The well-formed and uniform DOPhCz SAM layer promotes more homogeneous perovskite nucleation and improved crystallinity, lowering interfacial defect density and enhancing device performance compared with phosphonic-acid-based [2-(9Hcarbazol-9-yl)ethyl]phosphonic acid (2PACz)M. In addition, DOPhCz accelerates hole extraction and reduces chemical perturbation during device operation. As a result, the DOPhCz-based Sn─Pb PSC achieves a power conversion efficiency of 24.17%, outperforming its 2PACz-based counterpart (22.87%) and exhibiting significantly improved operational stability. When applied in all-perovskite tandem solar cells, a high efficiency of 28.30% is obtained. This work establishes a coherent mechanism for SAM-induced interfacial stabilization and provides valuable insights for molecular engineering of high-performance all-perovskite tandem devices.

A tailored in situ dual-interface modulation strategy is developed, capitalizing on the TTF-related multiple interactions and self-assembled interfacial enrichment distribution. This approach effectively regulates the crystallization dynamics, balances Sn ion distribution, promotes the carrier extraction and transfer across both the perovskite bulk and the dual interfaces, as well as stabilizes the perovskite structure, achieving high-performance Sn─Pb PSCs and all-perovskite TSCs.

ABSTRACT

All-perovskite tandem solar cells (TSCs) show great promise as the next-generation photovoltaic technology with high theoretical efficiency and low fabrication cost. However, further progress in the TSCs is critically hampered by the subpar performance of mixed tin-lead narrow-bandgap bottom subcells, which arises from the uncontrolled crystallization, unbalanced Sn²⁺ oxidation, and undesirable band alignment. Here, we develop an in situ dual-interface modulation strategy for tin-lead (Sn─Pb) perovskite solar cells (PSCs) by incorporating planar rigid tetrathiafulvalene (TTF) into the precursor solution. The interactions between electron donor TTF and Sn─Pb perovskite precursor constituents, coupled with the in situ self-assembled dual-interface enrichment of TTF, collectively regulate the crystallization dynamics, homogenize the Sn oxidation states, facilitate the carrier extraction and transport in the perovskite bulk and dual interfaces, and stabilize the perovskite structure. Such improvements enable homogeneous single-junction Sn─Pb PSCs to achieve a champion power conversion efficiency (PCE) of 24.30%, together with a record-high fill factor of 83.59% and excellent stability. Furthermore, we obtained a high PCE of 29.14% (certified 29.07%) in all-perovskite TSCs. Encapsulated tandem retains 80% of its initial efficiency following 964 h of maximum power point tracking under simulated 1-sun illumination in ambient air.

Employing a homology-guided strategy, we developed interlayer materials by grafting zwitterionic sidechains onto a pentacyclic fused-ring electron acceptor, affording high electron mobility, desirable interfacial compatibility while concurrently modulating the cathode/active-layer interface and promoting photocurrent generation via hole/energy transfer. These combined effects render multifunctional cathode interlayers with good versatility and exceptional thickness tolerance for 21.07% efficiency single-junction organic solar cells.

ABSTRACT

The performance evolution of organic solar cells (OSCs) is increasingly constrained by a growing mismatch between state-of-the-art photoactive layers and conventional cathode interlayer materials (CIMs). Here, we report a homology-guided molecular design strategy to synchronize CIM with fused-ring electron acceptors (FREAs). Grafting zwitterionic sidechains onto the high-performance pentacyclic FREA, we created a novel CIM, SZ1. This design grants SZ1 a deeper lowest unoccupied molecular orbital energy level, higher electron mobility, and superior interfacial compatibility compared to the perylene diimides-based counterpart. SZ1 simultaneously lowers the cathode work function and elevates the active layer's work function, facilitating Ohmic contact and enhancing electron extraction. SZ1 also acts as a supplemental light-harvester, with hole/energy transfer at the SZ1/polymer interface contributing to photocurrent generation. These attributes make SZ1 a highly efficient and versatile CIM with an optimal thickness near 30 nm and exceptional thickness tolerance, retaining ∼89% of peak performance even at a thick interlayer of 90 nm. An impressive efficiency of 21.07% is achieved, ranking among the most efficient OSCs. The generality of this homology concept is demonstrated by its successful extension to non-fused ring electron acceptors. This work establishes a transformative design paradigm for multifunctional, thickness-insensitive interlayers, paving the way for commercially viable OSCs.

Nature Energy, Published online: 07 January 2026; doi:10.1038/s41560-025-01939-x

This work demonstrates that incorporating the fluorescent small molecule SD-EDOT into the PM6:BTP-eC9 blend mitigates the V _oc–J _sc trade-off. SD-EDOT reduces energetic disorder, forms an energy cascade, promotes efficient charge generation, and suppresses non-radiative recombination. Consequently, ternary organic solar cells achieve simultaneously enhanced V _oc and J _sc, boosting the power conversion efficiency from 18.75% to 20.72%.

ABSTRACT

Though organic solar cells (OSCs) have achieved remarkable progress recently, the intrinsic limitation of the “seesaw effect” between open-circuit voltage (V _oc) and short-circuit current density (J _sc) hinders their further improvements. In this study, a fluorescent small molecule, namely SD-EDOT, is incorporated into the widely used PM6:BTP-eC9 system to overcome this challenge. The addition of SD-EDOT lowers the energetic disorder and electron–phonon coupling within the system. More importantly, it forms an energy cascade between donor and acceptor, enabling a side cascade energy transfer pathway and a more favorable energetic landscape. The high fluorescent property of SD-EDOT improves the utilization rate of high-energy excitons. These effects collectively promote faster and more efficient charge generation (improving J _sc), deeper highest occupied molecular orbit of donors, and suppressed non-radiative energy loss (elevating V _oc). Consequently, the ternary devices achieve simultaneously higher V _oc and J _sc, significantly boosting the power conversion efficiency from 18.75% to 20.72%. This study provides a rational strategy for mitigating the V _oc–J _sc trade-off by incorporating a highly fluorescent third component with tailored energy levels, offering a promising pathway toward higher-performance OSCs.

A guanidyl-engineered SAM strategy is developed to establish electrostatic–coordination synergy, effectively suppressing SAM aggregation, optimizing energy-level alignment, and passivating buried interface defects. This approach enables record efficiencies in wide-bandgap single-junction perovskite solar cells and laminated perovskite/silicon tandems, with exceptional operational stability. By resolving key interfacial challenges, this work offers a practical route toward scalable, durable, and high-efficiency tandem photovoltaics for sustainable energy applications.

ABSTRACT

Wide-bandgap inverted perovskite solar cells (PSCs) have attracted significant interest owing to their excellent stability feature and unique compatibility with tandem device architectures. However, two major challenges remain: the inhomogeneity of self-assembled monolayers (SAMs) and the insufficient passivation of buried interface defects. In this study, we introduce polyhexamethylene guanidine hydrochloride (PHMG) as an additive to 4-(7H-dibenzo[c,g]carbazole-7-yl) phosphonic acid (4PADCB) SAMs, wherein guanidyl groups in PHMG establish electrostatic–coordination synergy with 4PADCB and perovskite species, respectively. The electrostatic interaction suppresses SAM aggregation, reduces interfacial defects, and optimizes energy-level alignment at the SAM/perovskite interface, while the coordination effect promotes perovskite crystallization, enlarges grains, reduces defect densities, and relaxes interface stress. Consequently, the optimized 1.68 eV-bandgap PSC delivers a remarkable power conversion efficiency (PCE) of 23.62%, representing the highest value reported to date, with over 95% efficiency retention after 1300 h of thermal aging at 85°C in N₂. Furthermore, these PSCs are integrated into perovskite/silicon tandem solar cells, achieving a record PCE of 32.49% for a laminated tandem device and the superior values of 32.25% (with an active area of 1 cm²) and 29.34% (with an active area of 20 cm²) for monolithic tandem devices.

We report two novel dimerized small-molecule acceptors for ternary organic solar cells. The optimized device achieves a high power conversion efficiency of 20.26 % and demonstrates exceptional operational stability, retaining over 86 % of initial PCE after 1430 h under high humidity. A 15.6 cm² module also shows 17.63 % efficiency, proving the strategy's scalability for high-performance OSCs.

ABSTRACT

Organic solar cells (OSCs) are a promising renewable energy technology; however, balancing the power conversion efficiency (PCE) with long-term stability remains challenging. Herein, we report two novel dimerized small-molecule acceptors (DSMAs), GSNS-EH and GSNS-C8, that feature electron-rich planar pyrrolodithiophene bridges with tailored side chains. The optimized acceptor, GSNS-EH, with a branched 2-ethylhexyl chain, exhibited enhanced crystallinity and molecular ordering, reduced non-radiative losses, and improved blend morphology when incorporated into the PM6:BTP-eC9 host system as a third component. The resulting ternary OSC exhibited a PCE of 20.26 %, which is among the highest values reported for DSMA-based ternary devices. Moreover, the GSNS-EH-based cell exhibited exceptional operational stability, maintaining 86.7 % of its initial PCE after 1430 h of maximum power point tracking under high humidity (85 % ± 10 %) and 97.2 % after 1460 h at 85°C. The excellent scalability of this approach is demonstrated by a 15.6 cm² module achieving a high PCE of 17.63 %. Thus, this study provides an effective molecular design strategy toward highly efficient, stable, and scalable OSCs.

To enable simultaneous multi-defect passivation and interfacial free-volume reduction for high-performance perovskite solar cells, three hole-transport materials featuring distinct fluorine distribution are systematically designed and compared. Benefiting from better interfacial passivation ability, lower interfacial free-volume, more intimate interface contact, and enhanced suppression of ion migration and perovskite degradation, AdF-BCz-based devices achieved a champion efficiency of 25.35% and excellent stability.

Abstract

Interfacial defects and free-volume between the perovskite layer and hole transport material (HTM) critically impact the efficiency and stability of perovskite solar cells (PSCs). In this work, the interfacial issues of the PSCs are addressed by strategically modulating the fluorine distribution in N,N′-bicarbazole (BCz)-based HTMs, specifically, fluorine is introduced either asymmetrically and symmetrically on the peripheral groups, yielding AdF-BCz and SdF-BCz, respectively. Through a combination of experimental characterization and atomistic molecular dynamics simulations, it is demonstrated that AdF-BCz exhibits superior interfacial passivation stability against Pb²⁺ and I^– related defects, as well as stronger adhesion to the perovskite surface compared to the fluorine-free NF-BCz and symmetrically substituted SdF-BCz. Moreover, AdF-BCz reduces interfacial free-volume, promotes more intimate contact at the interface, and enhances the suppression of ion migration and perovskite degradation. Consequently, the PSCs fabricated with AdF-BCz achieved a notable efficiency of 25.35%, outperforming devices based on SdF-BCz (23.12%) and NF-BCz (24.2%). Furthermore, unencapsulated AdF-BCz based PSCs exhibit respectable stability, retaining 97% of their initial efficiencies after 2000 h under 30% relative humidity and 82% after 300 h of continuous heating at 85 °C.

This work devises a reflective semitransparent photovoltaic (R-STPV) structure, which exploits a dual-surface reflection optical path to achieve equivalent transmission. By integrating a reflector that selectively reflects visible light, such a design enables a high-performance Si-based R-STPV with 14.4% efficiency and 92.2% visible light transmittance, setting a record light utilization efficiency of 13.28% among STPVs.

Abstract

Semitransparent photovoltaics (STPV) show great potential for building integration, but the imbalance between visible light transmission and power generation limits their practical applications. To overcome this, a reflective STPV (R-STPV) structure is proposed, via utilizing a dual-surface reflection optical path to achieve equivalent transmission. Unlike STPV systems relying on transmission optical paths, this design bypasses reflection losses and alleviates the stringent selective absorption requirements for the active layer. Thus, such design enables the fabrication of wavelength-selective STPVs using various high-performance photovoltaic materials such as silicon, CIGS, and CdTe. As a proof-of-concept, an optical reflector is designed to selectively reflect visible light and transmit the invisible one, and by integrating it with the above PVs, we demonstrate high-performance R-STPV with appropriate optical geometry. Remarkably, the best Si-based R-STPV delivers a reliable efficiency of 14.4%, an average visible light transmittance of 92.2%, a record light utilization efficiency of 13.28% and an exceptional color rendering index of 99%. The versatility of R-STPV window technology makes it suitable for various building-integration application scenarios, and an average annual power generation of 69.8 kWh year m^{− 2} is obtained according to the simulation results. Therefore, this work paves a new path for high-performance solar windows that will contribute significantly to energy sustainability.

Wide-bandgap perovskite solar cells (PSCs), especially those with a bandgap ≈1.84 eV, are pivotal for tandem photovoltaics. However, severe halide phase segregation and ion migration critically limit their efficiency and operational stability. In this work, these challenges are addressed through an innovative Yb³⁺-based additive engineering strategy. Based on this strategy, the champion Yb(TFSI)₃-modified PSCs achieved a PCE of 19.06%.

Abstract

Phase segregation remains one of the most critical challenges limiting the performance and long-term operational stability of wide-bandgap perovskite solar cells (PSCs). This issue is especially pronounced in 1.84 eV wide-bandgap (WBG) perovskites, where severe halide phase segregation leads to compositional heterogeneity and accelerated device degradation. In this work, a comprehensive investigation of halide ion distribution across the surface and bottom interfaces of 1.84 eV perovskite films is conducted, revealing significant Br⁻/I⁻ halide phase segregation that severely impairs device efficiency and stability. To address this, Ytterbium (III) trifluoromethanesulfonate (Yb(TFSI)₃) is introduced as a multifunctional additive in the perovskite precursor. The strong coordination between Yb³⁺ ions and halide anions not only modulates the crystallization kinetics but also homogenizes the spatial distribution of Br-rich and I-rich domains, resulting in high-quality perovskite films with reduced compositional heterogeneity. Furthermore, Yb³⁺ significantly suppresses halide migration and ion exchange processes, thereby enhancing phase stability. Depth-resolved characterizations, including grazing-incidence wide-angle X-ray scattering, confirm improved crystallinity, structural uniformity, and suppressed phase segregation across the film depth. As a result, the champion device achieves an outstanding power conversion efficiency (PCE) of 19.06% and retains 85% of its initial efficiency after 1500 h in a nitrogen atmosphere (10% RH, 25 °C).

We report a doping strategy incorporating potassium cyanate (KOCN) additive into the 1.67 eV wide-bandgap perovskite precursor to regulate crystallization kinetics, promote (110) preferred orientation, and passivate uncoordinated lead ions and halide vacancies. The KOCN-based perovskite solar cells achieve a champion efficiency of 23.60% with an open-circuit voltage of 1.263 V, enabling two-terminal perovskite/silicon tandem cells with an efficiency of 31.10%.

ABSTRACT

Wide-bandgap (WBG) perovskite solar cells are crucial for efficient perovskite/silicon tandem solar cells (PSTSCs). However, they often suffer from uncontrolled crystallization, phase instability, and non-radiative recombination losses due to crystallographic defects. Here, we report a facile strategy of regulating perovskite crystallization and passivating uncoordinated lead ions and halide vacancies by adding potassium cyanate (KOCN) into the perovskite precursor, which incorporates into the perovskite lattice to thereby suppressing non-radiative recombination. Moreover, KOCN modulates nucleation to promote a (110) orientation and releases strain. Consequently, KOCN-based 1.67 eV-WBG perovskite devices yield a champion efficiency of 23.60% with an impressive open-circuit voltage of 1.263 V and fill factor of 84.39%, enabling a 31.10% efficiency in two-terminal PSTSCs. After 1600 h of aging in the glovebox, the KOCN-doped device retains over 98% of its initial efficiency.

Perovskite solar modules face environmental risks from lead and iodine leakage. A dual-function adsorbent—porphyrin-modified whitlockite nanocomposites—effectively captures iodine and Pb^{2 +}, even under severe damage. Combined with a semi-closed recycling process, it recovers 96.9% high-purity PbI² and reduces residual Pb^{2 +} to <10 ppb, offering an integrated “protection–recycling” solution for sustainable perovskite photovoltaics.

ABSTRACT

The environmental hazards posed by the release of toxic lead ions (Pb²⁺) and volatile iodine species remain a major obstacle to the large-scale commercialization of perovskite solar modules. Here, we propose a dual-function adsorbent–porphyrin-modified whitlockite nanocomposites (WH&Por), which simultaneously captures volatile iodine via surface-coated porphyrin and adsorbs Pb²⁺ through the whitlockite matrix, forming an integrated pollutant barrier throughout the entire lifecycle of perovskite devices. Experimental results show that even under severe mechanical damage with a WH&Por loading of just 0.25 mg/cm², the protection system prevents the leakage of lead and iodine, demonstrating excellent environmental safety performance. In addition, we developed a semi-closed loop recycling process that enables the recovery of high-purity PbI₂ from perovskite waste, achieving a recovery yield of up to 96.9%. Devices reassembled using the recovered PbI₂ exhibit power conversion efficiencies comparable to those of their pristine counterparts. Remarkably, the residual Pb²⁺ concentration in the treated recycling waste solution was reduced to below 10 ppb, well beneath the stringent limit set by the European Union Drinking Water Directive 98/83/EC. This study offers a practical and integrated “protection–recycling” solution to one of the key environmental challenges facing perovskite photovoltaics.

Molecular-integrated PDA(AcSH)₂ enables field-effect passivation via PDA²⁺ at the perovskite/C₆₀ interface, while AcSH^– mediates crystal growth and trap passivation. Reducible ─SH in AcSH^– converts I₂/I₃ ^– to I^–, forming reversible S─S dimers for self-healing and stability. The device achieves 26.88% efficiency (certified 26.4%) with a minimal non-radiative voltage loss of only 64 mV.

Abstract

Severe interfacial energy loss and inferior crystal quality remain key limitations for high-performance perovskite solar cells (PSCs). Herein, we report a multifunctional molecule, 1,3-propanediamine dimercaptoacetate (PDA(AcSH)₂), designed through a molecular-integration strategy to address these challenges simultaneously. The PDA²⁺ cations preferentially accumulate at the perovskite/C₆₀ interface, establishing a field-effect passivation that suppresses interfacial contact induced non-radiative recombination. Meanwhile, the AcSH^– anions are homogeneously distributed throughout the perovskite layer, mediating crystal growth and passivating charged traps via dual binding of ─SH and ─COO^– groups. The reducible ─SH groups in AcSH^– also convert photo-thermally generated I₂/I₃ ^– species into I^–, forming reversible S─S dimers that photodecompose under UV light illumination to regenerate ─SH groups. This enables a self-sustaining redox cycle for dynamic defect healing and enhances both precursor and film stability. Consequently, the optimized small-area (0.09-cm²) device achieves impressive efficiency of 26.88% and a non-radiative voltage loss of only 64 mV. The strategy is readily scalable, delivering efficiencies of 24.92% and 22.73% for 1-cm² device and 12.96-cm² mini-module, respectively. This work highlights the effectiveness of rational molecular design in mitigating both bulk and interfacial energy losses, paving the way for the next generation of high-performance, stable, and scalable PSCs.

A study on two pyridine-based passivators, flexible 2PYET and rigid 2PYBEN, reveals how backbone flexibility dictates performance. The flexible core of 2PYET not only enhances defect-coordinating ability but, crucially, suppresses detrimental molecular aggregation. This facilitates a uniform, ordered passivation layer on the perovskite surface, which is key to achieving high performance and operational stability.

Abstract

Molecular modulation of the perovskite/C₆₀ interface to reduce defect density plays a decisive role in achieving high-efficiency and stable inverted perovskite solar cells. However, the impact of substituent flexibility on passivation performance remains insufficiently understood. Here, two structurally analogous pyridine-based molecules with distinct central substituents 1, 2-bis(4-pyridyl) ethane (2PYET) featuring a flexible alkyl chain and 1, 4-di(4-pyridyl) benzene (2PYBEN) possessing a rigid phenyl core are designed to elucidate the role of molecular flexibility in perovskite surface passivation. Our study reveals that the flexible central substituent significantly enhances the electron cloud density of the pyridine groups, thereby improving their passivation capability, while simultaneously suppressing molecular aggregation and promoting better interfacial contact. As a result, devices modified with 2PYET achieved a champion power conversion efficiency of 26.03% for 0.09 cm² devices and 24.45% for 1.0 cm² devices.

Through synergistic engineering of polar zwitterionic and non-polar sidechains, simple non-fused ring electron acceptors (NFREAs) were converted into efficient cathode interlayers (zNFREAs). The optimized material exhibits exceptional thickness insensitivity, broad compatibility across various systems, enabling 20.73% efficiency organic solar cells with good operational stability.

Abstract

Advancing organic solar cells (OSCs) require simultaneous progress in organic semiconductors for both active layers and interlayers. The disparate electronic and structural properties of electron acceptors and interlayers present a significant challenge to optimal interfacial compatibility. Herein, we report four zwitterionic non-fused-ring electron acceptors (zNFREAs) as interlayer materials, featuring a simple thiophene–benzene–thiophene core and 5,6-difluoro-1,1-dicyanomethylene-3-indanone terminals, affording low synthetic complexity and low-lying energy levels. Synergistic modulation of central polar and peripheral non-polar sidechains effectively tunes optoelectronic properties and molecular aggregation. TBT-TMZ, integrating central hexyl-pendant zwitterionic groups with peripheral 2,4,6-trimethylphenyl substituents, exhibits favorable solubility and work function tunability, a well-balanced crystallinity and film-forming ability, as well as desirable active layer compatibility. PM6:Y6-based devices incorporating TBT-TMZ achieve a power conversion efficiency (PCE) of 18.21%, retaining approximately 90% of their peak PCE even with TBT-TMZ layers at a thickness of 101 nm, demonstrating exceptional thickness insensitivity. Furthermore, TBT-TMZ displays broad compatibility with diverse active layers, delivering an outstanding PCE of 20.73% for the D18:BTP-eC9:L8-BO blend. This work not only introduces an innovative class of zwitterionic materials based on state-of-the-art NFREAs but also sheds light on the critical role of systematical polar and non-polar sidechains optimization toward high performance water/alcohol-soluble n-type organic semiconductors.

The low-pKa hexafluoroisopropanol (HFIP) was introduced as solvent to replace isopropanol (IPA) for passivators. HFIP possesses a weaker proton-donating ability rather than proton-acceptation ability compared to IPA, reducing the possibility of deprotonation of ammonium salts (R-NH₃ ⁺) to amines (R-NH₂). Finally, the perovskite solar cell with HFIP/PDAI treatment achieved an efficiency of 26.91% with enhanced long-term stability

Abstract

Various passivation strategies have been explored to enhance the stability of the perovskite solar cells (PSCs). However, the chemical stability of passivators has received limited attention. This study investigates replacing conventional isopropyl alcohol (IPA) with hexafluoroisopropanol (HFIP) as the solvent for depositing passivation layers on perovskite films, offering a novel approach to minimizing defects and improving photovoltaic performance. The unique properties of HFIP, particularly its low pKa and strong proton-donating ability, effectively inhibit the deprotonation of organic ammonia salts. As a result, the HFIP-based passivation solution exhibits enhanced chemical stability, leading to highly reproducible PSCs fabrication. Additionally, perovskite films treated with the HFIP passivation solution demonstrate higher photoluminescence (PL) intensity and longer carrier lifetimes. Consequently, PSCs treated with HFIP-based 1,3-propanediamine dihydroiodide (PDAI) solution achieved a champion power conversion efficiency (PCE) of 26.91% (certified PCE of 26.88%) and maintained 95.9% of their initial efficiency under operational conditions for 1000 h.

We develop a novel interface molecular locking (IML) strategy synergized with self-assembled monolayer (SAM) for perovskite solar cells. A high-coverage hole-selective layer is formed through combining the advantages of two SAMs. Additionally, thiabendazole is introduced into the perovskite precursor to achieve molecular locking at the buried interface. Consequently, the optimized devices achieve efficiencies exceeding 26.0% with enhanced stability.

Abstract

The uniformity of self-assembled monolayers (SAMs) and the interfacial defects in perovskite films significantly affect the performance of inverted perovskite solar cells (IPSCs). Herein, we develop an innovative interface molecular locking (IML) strategy synergized with SAMs to enhance the properties of buried interface. Specifically, two SAMs—(4-(3,6-dimethoxy-9H-carbazol-9-yl)phenyl)phosphonic acid (MeO-PhPACz) and 5-indoleboronic acid (5-IBA)—are employed to combine their advantages and form an enhanced SAM (E-SAM). Due to the strong π–π interactions between MeO-PhPACz and 5-IBA, the E-SAM exhibits a denser and more uniform morphological coverage. Introducing thiabendazole (TBZ) additive into the perovskite precursor further ameliorates the buried interface properties through its self-assembly behavior, owing to its large molecular dipole moment and strong interactions with the E-SAM. This strategy not only achieves favorable energy level alignment but also improves the crystallinity and reduces the trap density of perovskite films, thereby significantly enhancing hole extraction and suppressing non-radiative recombination. Consequently, both (FA_0.95MA_0.05)_0.95Cs_0.05Pb(I_0.95Br_0.05)₃ and FA_0.95Cs_0.05PbI₃-based IPSCs achieve high efficiencies exceeding 26.0%, along with significantly enhanced stability. Notably, (FA_0.95MA_0.05)_0.95Cs_0.05Pb(I_0.95Br_0.05)₃ solar cells deliver a high voltage of 1.21 V, one of the highest reported among IPSCs with a 1.56 eV bandgap. Our findings provide unique insights into achieving high-performance IPSCs by synergistically engineering buried interface.

Nature Communications, Published online: 03 January 2026; doi:10.1038/s41467-025-68125-1

Nature Communications, Published online: 05 January 2026; doi:10.1038/s41467-025-68213-2

Nature Photonics, Published online: 06 January 2026; doi:10.1038/s41566-025-01819-6

Nature Photonics, Published online: 06 January 2026; doi:10.1038/s41566-025-01809-8

Nature Energy, Published online: 31 December 2025; doi:10.1038/s41560-025-01930-6

Nature Energy, Published online: 31 December 2025; doi:10.1038/s41560-025-01903-9

Nature Energy, Published online: 05 January 2026; doi:10.1038/s41560-025-01932-4

Nature, Published online: 31 December 2025; doi:10.1038/d41586-025-04021-4

2,5-thienedicarboxylic acid (TDCA) with dual bonding sites is used as interfacial connecting bridge to fill the voids between Me-4PACz molecules to form a denser HSL. Furthermore, the C═O groups and S atom in TDCA can chelate with uncoordinated Pb²⁺ in perovskite, effectively passivating buried interface defects. Consequently, the PSCs based on TDCA interface layer achieved a champion PCE of 26.15%.

ABSTRACT

[4-(3,6-dimethyl-9H-carbazol-9yl)butyl]phosphonic acid (Me-4PACz) self-assembled monolayers (SAMs) as hole-transport layers (HTLs) have enabled remarkable performance in inverted perovskite solar cells (PSCs). However, the uneven coverage and terminal carbazole groups of Me-4PACz SAMs cannot effectively passivate defects, which constrains further improvements in device performance. Herein, we use post-assembled chelating molecular bridge strategy to introduce 2,5-thiophenedicarboxylic acid (TDCA) as interface layer between Me-4PACz HTL and perovskite layer, which not only ensures the priority deposition of the primary Me-4PACz SAM, but also fills voids within the Me-4PACz HTL to form dense and uniform bilayer HTL. In addition, the C═O groups and S atom in TDCA can chelate with uncoordinated Pb²⁺ in perovskite, effectively passivating buried interface defects. Consequently, the PSCs based on TDCA interface layer achieved a champion PCE of 26.15%. It is noteworthy that this strategy has excellent process compatibility. The PCE of narrow-bandgap (1.55 eV) and wide-bandgap (1.77 eV) PSCs are 26.20% and 21.65%, respectively. Furthermore, the corresponding PSCs maintain more than 94.2% and 90.7% of initial efficiency after 2500 h in a glove box and 1000 h under one-sun illumination, respectively. This work provides a promising buried interface molecular bridge strategy for high-performance PSCs.