Although perovskite/organic tandem solar cells have many advantages, their power conversion efficiency (PCE) still substantially lags behind their perovskite/perovskite counterparts. One of the main reasons is the low external quantum efficiency and high energy loss of the rear subcell. In this work, guided by the semi-empirical analysis, the most suitable available material combination has been obtained. To further improve the photovoltaic performance of the organic rear cells, isopropanol has been used as a co-solvent additive to finely tune the bulk heterojunction morphology of the active layer. Together with the optimization of each subcell, a remarkable PCE of 26.49

The bulk heterojunction (BHJ) configuration has immensely boosted the power conversion efficiencies (PCEs) of organic solar cells (OSCs). Nevertheless, precise control over donor/acceptor microstructures within BHJ films remains challenging, due to their intertwined self-assembly process during solution casting, thus limiting device performance. Herein, we report a dual-additive targeted engineering strategy to synergistically regulate the donor and acceptor aggregation structures in BHJ blends via introducing two types of additives with distinct characteristics. Specifically, it is found that the solid additive featuring twisted bulky groups (e.g., DBM) can effectively decelerate crystallization kinetics of the polymer donors, thus alleviating their over-aggregation and promoting molecular ordering. Distinctively, the solvent additive with linear or co-planar configurations (e.g., DIO or 1-CN) can induce enhanced pre-aggregation and also more ordered packing of the small molecule acceptors via their special intermolecular interactions. Intriguingly, these two different types of additives can operate collaboratively rather than interfering with each other. Ultimately, the PM6:L8-BO-based OSC processed with DIO+DBM achieves a notable PCE of 20.1% with superior photostability. The universality of this strategy is validated across various blend systems. In D18:L8-BO:BTP-S10 system, a champion PCE of 20.9% (certified as 20.6%) is attained. This study provides an effective pathway for dual-phase morphological modulation toward high-performance OSCs.

The nanoscale morphology of the active layer critically governs the performance of organic solar cells (OSCs), where the molecular packing and phase organization of small-molecule acceptors play a decisive role. Although solvent additives are widely used to regulate morphology, their volatility often compromises reproducibility and long-term stability. Here, we systematically investigate four positional isomers of dibromonaphthalene (DBN): 1,8-, 1,5-, 2,7-, and 2,6-DBN, as solid-state additives in PM6:Y6-based OSCs. Despite identical chemical compositions, the DBN isomers exhibit distinct molecular symmetry and crystallization kinetics, leading to fundamentally different impacts on acceptor aggregation and phase organization. Among them, 2,6-DBN, featuring a highly symmetric configuration and moderate supercooling, enables balanced crystallization kinetics during thermal annealing. This kinetically accessible ordering promotes compact π-π stacking, favorable vertical phase distribution, and reduced energetic disorder in the active layer. Consequently, charge carrier mobility is enhanced, non-radiative recombination losses are suppressed, and balanced charge transport is achieved, yielding a champion power conversion efficiency of 19.65% in PM6:Y6 devices. These results highlight crystallization kinetics, rather than additive crystallinity alone, as a key determinant for morphology control, providing a generalizable strategy for rational solid additive design in high-performance OSCs.

Electropolymerized Co(III) and Fe(II) metallopolymers exhibit ternary and binary nonvolatile memristive behaviors, respectively, owing to their distinct redox characteristics.

Stochastic molecular packing within the fullerene electron transport layer (ETL) and severe trap-mediated recombination at the perovskite/ETL interface represent the primary bottlenecks limiting the open-circuit voltage (Voc) of inverted wide-bandgap perovskite solar cells. We report a supramolecular orchestration strategy achieved by integrating a solution-processed non-fullerene acceptor, L8-BO, into the fullerene matrix. Theoretical simulations and structural characterizations reveal that L8-BO strengthens van der Waals and electrostatic interactions within the ETL, thereby suppressing disordered fullerene aggregation and enhancing electron mobility. At the interface, L8-BO forms robust supramolecular bonds with perovskite surface defects, passivating trap states and optimizing energy-level alignment. This dual-intrinsic and interfacial regulation improves charge extraction and substantially reduces Voc losses. Consequently, 1.78 eV wide-bandgap devices achieve a power conversion efficiency of 21.13% alongside an exceptional Voc of 1354.18 mV, equivalenting to 91.67% of the Shockley-Queisser limit. Moreover, these devices exhibit markedly improved operational stability, retaining high performance under accelerated thermal and light-soaking stress.

Polyaromatic materials, characterized by extended C-C/C = C conjugation, hold transformative potential for next‑generation plastic electronics. Herein, we present a click-like C = C bond-forming Aldol polycondensation that proceeds with exceptional efficiency and operational simplicity in air. Central to this finding is an enolate-mediated mechanism within a dual-catalytic process. Strategic control of adjacent heteroatom and ring geometry precisely modulates the proton transfer and the energy spans in the enol/enamine tautomerization pathways, thus the reactivity of ketone and imide monomers. This approach establishes both a design roadmap and a versatile tool box for tailored functionality. Notably, the in situ-generated acetic acid increases reactant oxidation potential enables air-tolerant operation, unlike conventional metal-catalyzed C-C couplings requiring oxygen-free conditions. This methodology facilitates rapid (typically within 30 min), modular assembly of multidimensional conjugated polymers, offering transformative potential for emerging plastic electronics and beyond.

Although perovskite/organic tandem solar cells have many advantages, their power conversion efficiency (PCE) still substantially lags behind their perovskite/perovskite counterparts. One of the main reasons is the low external quantum efficiency and high energy loss of the rear subcell. In this work, guided by the semi-empirical analysis, the most suitable available material combination has been obtained. To further improve the photovoltaic performance of the organic rear cells, isopropanol has been used as a co-solvent additive to finely tune the bulk heterojunction morphology of the active layer. Together with the optimization of each subcell, a remarkable PCE of 26.49% (certified 25.56%) with a high open-circuit voltage of 2.214 V has been achieved for the perovskite/organic tandem device.

Solid additives (SAs) have been proven as a useful strategy to finely tune the morphology of organic solar cells (OSCs). However, the most commonly used SAs are toxic and require high loading concentrations during fabrication, generating material waste and sustainability challenges. Here, we report a flavoring compound, 1,4-dithiane (DTA), as a green SA. It was found that DTA can interact synergistically with both the donor and acceptor. By inducing donor crystallization ahead of the acceptor, DTA creates a polymer network framework first. This framework guides the following crystallization of acceptor, thus leading to an optimized morphology in active layers. As a result, PM6:L8-BO binary devices processed with DTA achieve a power conversion efficiency (PCE) of 19.64% with a high fill factor (FF) of 81.1%, significantly surpassing the pristine device's PCE of 18.48%. The confluence of high efficiency, enhanced eco-compatibility, and minimal additive dosage establishes DTA-mediated morphology control as a viable pathway toward commercial OSC technologies.

Controlling active-layer morphology without processing additives remains a core challenge for high-efficiency organic solar cells (OSCs), particularly for molecular-weight-sensitive polymer donors. Here, we report an additive-free morphology control strategy based on molecular-weight-mediated aggregation kinetics using the benchmark donor polymer D18. We show that both low- and high-molecular-weight D18 exhibit aggregation behavior mismatched to the nonfullerene acceptor L8-BO, causing to suboptimal film formation. By blending D18 with different molecular weights, the donor aggregation time window is broadened and moderated, enabling kinetically synchronized film formation without additive assistance. As a result, additive-free D18-mix:L8-BO devices deliver a high power conversion efficiency of 20.0% with balanced charge transport and suppressed recombination, while maintaining efficiencies above 19% over a wide blending range. Moreover, this intrinsic kinetic regulation strategy is compatible with advanced device architectures and scalable fabrication: ternary D18-mix:L8-BO:AITC devices achieve an enhanced efficiency of 20.5%, and large-area modules (17.14 cm2) retain an efficiency of 17.2%. This work establishes molecular weight as an intrinsic kinetic handle for additive-free morphology control, offering a robust and scalable materials strategy for high-performance OSCs.

Simultaneously minimizing energy loss and optimizing charge dynamics remains a central challenge for further boosting the photovoltaic performance of organic solar cells (OSCs). As a key parameter controlling charge generation, transport, and recombination kinetics, film morphology is also closely linked to energetic disorder and therefore plays a crucial role in determining non-radiative recombination. Herein, a series of halogenated thiazole units (2,4-2DCl, 2Br-4Cl, and 2,4-DBr) are rationally designed for the precise regulation of film morphology. Among these solid additives, 2,4-DBr exhibits moderate molecular interactions with PM6 and L8-BO, which not only suppress over-aggregation but also promote the formation of ordered packing with a favorable interpenetrating network structure. Consequently, the PM6:L8-BO-based OSCs treated with 2,4-DBr achieve a higher efficiency of 19.65%, accompanied by a reduced voltage loss, benefiting from enhanced and balanced charge mobilities as well as suppressed energetic disorder. More impressively, the 2,4-DBr treated D18-based ternary devices deliver a remarkable efficiency of 21.10%, with a certified efficiency of 20.93% by CPVT, which ranks among the best values reported so far. This work highlights the critical role of rational halogenation strategies for solid additives in optimizing film morphology, thus enhancing charge dynamics and suppressing the energetic disorder of the active layer, thereby enabling high-performance OSCs.

Wide-bandgap (WBG) mixed-halide perovskites with high bromine (Br) content, which are used as the front-cell material in perovskite-organic tandem solar cells (TSCs), often exhibit initial halide-mixing inhomogeneity and light-induced halide segregation1-3, limiting the performance of perovskite-organic TSCs. Here we introduce a photo-transformable additive, 4-[3-(trifluoromethyl)-3H-diazirin-3-yl]benzylammonium salt (TDB), into the WBG perovskite precursor solution to establish a two-stage strategy for stabilizing the mixed-halide phase. During crystallization, TDB improves the initial halide homogeneity by suppressing the rapid precipitation of the Br-rich phase and accelerating halide mixing upon annealing. During operational illumination, TDB undergoes transformation to form a new species with stronger adsorption on the perovskite grain-boundary surfaces, which inhibits the formation of iodide-related defects and suppresses defect-assisted carrier trapping and ion migration, thereby mitigating light-induced halide segregation4-6. The representative WBG perovskite (bandgap energy (Eg) = 1.88 eV) solar cell had a power conversion efficiency (PCE) of 20.01%, with an open-circuit voltage of 1.42 V, a fill factor of 85.13% and improved stability under illumination. By integrating the WBG perovskite solar cell into a monolithic perovskite-organic TSC, we achieved a PCE of 28.80%, with a certified steady-state PCE of 28.04%. The perovskite-organic TSC retained 90% of its initial PCE after 625 h of operation under the ISOS-L-1 protocol.

Perovskite-organic tandem solar cells (POTSCs) have emerged as a promising strategy to transcend the thermodynamic Shockley-Queisser limit of single-junction devices. This architecture uniquely combines the exceptional tunability of wide-bandgap (WBG) perovskite front cells with narrow-bandgap (NBG) organic rear cells. In this review, we systematically examine the critical challenges and advancements in POTSCs. For the WBG perovskite subcells, we focus on composition engineering for precise bandgap tuning, the underlying thermodynamic and kinetic mechanisms of phase segregation, energy loss pathways resulting from non-radiative recombination, and interface regulation strategies. Regarding the organic subcells, we highlight the necessity of exact bandgap matching and summarize molecular design strategies aimed at developing highly efficient NBG materials. Finally, we discuss the tandem architecture potential for achieving high power conversion efficiencies and synergistic stability. In this synergistic configuration, the WBG perovskite layer acts as a natural UV filter to protect the organic materials from high-energy photons, while the moisture-insensitive organic layer provides a barrier to shield the perovskite from water and oxygen erosion. By dissecting these key aspects, this review aims to provide a comprehensive roadmap for propelling POTSC efficiencies beyond the 30% milestone.

Scalable fabrication under ambient conditions is essential for scale-up organic solar cells (OSCs), yet confronting the challenge of rational morphology regulation in the blade-coated active layer. In this work, we develop BO-4I as a nucleating agent to address the undesirable aggregation behavior of blade-coated L8-BO acceptor film. The relatively weak backbone pi-stacking while strong alkyl-chain packing of BO-4I, effectively lower the nucleation barrier and moderate the aggregation kinetics of L8-BO, extending the reorganization window for ordered molecular packing. As a result, the collaborative regulation of BO-4I heterogeneous nucleating agent and air-knife treatment optimizes the crystallization and suppresses the disordered alkyl-chain entanglement of L8-BO, enabling desirable morphology in the blade-coated D18/L8-BO:BO-4I film under ambient conditions in air. Consequently, the collaborative treatment of BO-4I agent and air-knife for the D18/L8-BO-based device significantly elevates the power-conversion efficiency (PCE) from 9.88% to 19.41%, which is the highest value reported for the OSCs fabricated under ambient conditions in air. Particularly, such strategy enables a notable PCE of 14.75% in the D18/L8-BO:BO-4I-based flexible module with an active area of 11.9 cm2, demonstrating its practical application for scale-up flexible OSCs.

ABSTRACT Dimeric acceptors have recently emerged as promising giant molecule acceptors (GMAs) for organic solar cells (OSCs), but most systems link two identical monomeric units. Hybrid GMAs combining different acceptor units remain unexplored. Herein, we develop a core‐to‐wing type hybrid strategy coupling BT‐ and BZ‐core acceptor units through flexible ester‐linked alkyl chains, affording three GMAs (BTZ‐2‐2, BTZ‐2‐6, and BTZ‐2‐10). This design enables complementary absorption by combining the spectral features of BT‐ and BZ‐based monomers while preserving favorable crystallization behavior. Among them, BTZ‐2‐6 exhibits the broadest, most red‐shifted absorption, enhanced π‐π stacking, and the highest electron mobility due to the optimal length of its ester‐linked alkyl chain. The PM6:BTZ‐2‐6 binary device delivers 18.53% efficiency and retains nearly 90% of its initial efficiency after 720 h of illumination. Furthermore, the efficiency can be increased to 19.41% by replacing PM6 with D18 as the donor polymer, and further boosted to 20.25% by incorporating BTZ‐2‐6 as a third component into PM6:L8‐BO binary devices. These results demonstrate that core‐to‐wing hybrid GMAs with ester‐linked alkyl chains of different lengths provide an effective strategy for constructing high‐performance GMAs, offering new opportunities for efficient and stable OSCs.

Organic photovoltaics (OPVs) can have certified power conversion efficiencies exceeding 21%, placing them within a performance range relevant for commercialization. In this Review, we analyse OPV development through efficiency optimization, long-term operational stability, scalable processing and manufacturing cost. Strategies in active material design, additive engineering, self-assembled interlayers and synthetic-complexity control are summarized, highlighting how molecular structure, aggregation behaviour, interfacial energetics and material cost collectively govern device performance and degradation. Stability-limiting mechanisms arise across materials, bulk-heterojunction morphology and buried interfaces, underscoring the need to address the system-level coupling between these factors under realistic operating conditions. Developing OPVs towards real-world deployment will require environmentally friendly processability, thick-film tolerance, fluid-dynamics-regulated coating, mechanical flexibility and semi-transparent device architectures. Large-area modules exceeding 10 cm2 with power conversion efficiencies of ≥15% demonstrate progress towards scalable fabrication. By combining progress across materials, interfaces, device architectures and cost-aware design, applications such as wearable electronics, indoor energy harvesting, building-integrated photovoltaics and agrivoltaic systems can be realized. Organic photovoltaics (OPVs) now achieve efficiencies exceeding 21%, but commercialization depends on improving stability, scalability and cost alongside performance. This Review describes how advances in materials, interfaces and manufacturing can enable durable OPVs for applications including wearable, indoor and building-integrated energy harvesting.

The ultrathin metal electrode in semitransparent organic photovoltaics (STOPVs) usually suffers from limited charge collection capability and conductivity and thus hinders the power conversion efficiency (PCE). Herein, a new strategy of enhancing the π-delocalization of electron transport layer (ETL) via lithium bis(trifluoromethanesulfonyl)imide doping is developed. The enhanced π-delocalization in ETL benefits sizeable intermolecular π–π overlap, prone to harvesting electrons and thereby improving charge collection range. Doping also improves the conductivity of both ETL and ultrathin silver electrode. Furthermore, the trap densities in ETL and STOPV devices are reduced after doping, contributing to suppressed recombination and higher PCE. Consequently, ETL doping maintains an average visible transmittance of 30

The interconnecting layer (ICL) plays a critical role in series-connected tandem solar cells (TSCs). However, the PEDOT:PSS layer, commonly used hole transport layer in ICL, still exhibits non-negligible light absorption, which remains an obstacle to further improve the photovoltaic performance of TSCs. Here, we demonstrate an efficient strategy to mitigate optical and electrical losses in PEDOT:PSS-based ICLs by reconstructing PEDOT:PSS film via alkali metal carbonate (AMC) doping. AMC doping can increase the proportion of PEDOT in PEDOT:PSS thin films, allowing them to be ultra-thin but robust enough to isolate adjacent active layers. Comprehensive characterizations demonstrate that AMC doping promote increased transmittance, decreased resistance and optimized surface morphology for PEDOT:PSS films. Asa result, both the short-circuit current density (J(sc)) and power conversion efficiency (PCE) are improved after AMC doping in PEDOT:PSS for TSCs with different active layer combinations, exhibiting excellent universality in TSCs application. Notably, the PCEs of organic homo-TSCs and perovskite/organic TSCs with AMC doping reached 20.04 % and 26.05 %, respectively. Our work underscores the great potential of AMC doping in optimizing PEDOT:PSS films in ICL, offering an innovative pathway for fabricating highly efficient TSCs. (c) 2025 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Controlling morphological evolution during film formation is crucial for high-efficiency organic solar cells, yet complex intermolecular interactions often hinder controllable solution-to-solid growth, resulting in non-ideal blend microstructures. Here, we report a kinetic-gradient regulation strategy that enables programmable molecular self-assembly using a two-tier volatile solid additive (VSA) system with graded volatility. In this framework, highly volatile Tier-1 VSAs initiate early-stage acceptor nucleation and direct molecular packing, while lower-volatility Tier-2 VSAs prolong and relay additive-acceptor interactions into later drying stages. Additionally, by systematically tuning the halogen-bonding propensity and dipole moment of Tier-2 VSAs, both the strength and duration of additive-acceptor interactions are precisely regulated, enabling fine control over molecular self-assembly and donor-acceptor interdiffusion. The resulting films exhibit tighter, more ordered packing and well-regulated phase-separation length scales, extending exciton diffusion and suppressing trap states, thereby enhancing short-circuit current and fill factor. Consequently, D18:L8-BO-based binary devices achieve a champion efficiency of 20.5% (vs. 19.0% for the control) with improved photostability. This strategy also demonstrates scalability, delivering a 17.4% efficiency in large-area modules, and generality, enabling 20.8% efficiency in ternary D18:L8-BO:BTP-eC9 devices. Overall, this work establishes a kinetic regulation paradigm for precisely directing morphological evolution of bulk-heterojunction films toward high-performance organic photovoltaics.