SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-026-4312-8
Carbazole phosphonic acid-based self-assembled molecules (SAMs) serve as effective hole-selective contacts in organic solar cells (OSCs), yet their molecular packing and aggregation behavior during solution processing remain difficult to control, limiting hole transport and device durability. This study introduces a polymer-templated self-assembly strategy to regulate molecular organization by one-step spin-coating a blend of [2-(9H-carbazol-9-yl)ethyl]phosphonic acid (2PACz) and PEDOT:PSS. The polycationic PEDOT+ framework acts as a template, providing supplementary anchoring interactions that promote ordered molecular arrangement and suppress unfavorable agglomeration. Pronounced face-on orientation and enhanced structural coherence of 2PACz within the polymer matrix are evidenced. The templated ordering improves vertical charge transport, interfacial homogeneity, and film morphology. In binary OSCs based on PM6:BTP-eC9, the hybrid hole transport layers (HTLs) yield a champion power conversion efficiency (PCE) of 20.26%, with an open-circuit voltage (VOC) of 0.874 V, a short-circuit current (JSC) of 28.97 mA cm-2, and a fill factor (FF) of 80.02%. Devices incorporating hybrid HTLs exhibit exceptional operational stability, retaining over 90% of initial PCE (T90) after 405 h of continuous operation at the maximum power point (MPP). This work establishes polymer-directed SAM assembly as a scalable route to simultaneously optimize nanoscale molecular packing, interfacial energetics, and long-term device stability for high-performance OSCs.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-026-4391-5
Self-assembled monolayers (SAMs) enable precise tuning of the ITO/active layer interfacial dipole, yet their impact on the crystallization kinetics of the overlying active layer remains poorly understood, limiting their potential in high-efficiency organic solar cells. This study introduces THPC, a self-assembling material with an extended carbazole core and heteroatom substitution, as a hole transport layer (HTL). Unlike the hydrophilic PEDOT:PSS, THPC exhibits low surface energy, providing a favorable template that extends the film formation kinetics of the PM6:L8-BO-X blend by nearly 1.4 times, mitigating the explosive nucleation prevalent in PM6-based active layers. This promotes a highly ordered fibrous morphology and enhances vertical phase separation. The deep work function of THPC (5.32 eV) increases the built-in potential, reduces interfacial trap density, and facilitates charge extraction. Consequently, non-radiative recombination loss decreases from 0.243 eV to 0.227 eV, and the open-circuit voltage rises from 0.866 V to 0.883 V, yielding a power conversion efficiency (PCE) of 20.19%, outperforming the PEDOT:PSS control (18.67%). This finding is confirmed across multiple Y-series acceptors, all approaching 20% PCE. Notably, the D18:L8-BO system achieves a PCE of 20.55%, demonstrating broad applicability.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-025-3828-y
The rapid development of halogen-free solvent-processed organic solar cells (OSCs) has been enabled by side-chain modification on small molecular acceptors, yet the structure-property relationship between inner/outer chain lengths and device performance remains unclear. This study systematically investigates five non-fullerene acceptors (NFAs) with varied side-chain positions and architectures, clarifying the effects of inner versus outer modifications on energy level distribution, film morphology, and carrier dynamics. Notably, longer alkyl chains are not always superior; excessive solubility reduces molecular packing order. The optimized PM6:BTP-TO12 blend achieves a power conversion efficiency (PCE) of 18.2%. Furthermore, ternary OSCs incorporating BTP-TO12 as a guest material reach a remarkable PCE of 19.5%, enhancing the performance of L8-BO-based devices processed with green solvents. This improvement is attributed to the low energy loss and well-controlled aggregation behavior of BTP-TO12 in environmentally friendly toluene. These findings establish a design guideline for side-chain engineering in green-solvent-processed OSCs, achieving state-of-the-art performance and advancing scalable, eco-compatible photovoltaic technologies.
SCIENCE CHINA Materials•2026•DOI: 10.1007/s40843-025-3628-3
The solution aggregation structures of conjugated polymers are pivotal in determining their film morphology and optoelectronic properties, yet the relationship between solution aggregation and device performance remains elusive in organic photodiode (OPD) systems. Herein, we introduce the first examination of solution aggregation structures of all-polymer OPD blends, with a focus on how molecular entanglement modulates aggregation behavior and subsequent photodiode performance of low-cost poly(3-pentylthiophene). Using small-angle neutron scattering and freeze-dried imaging, we provide a comprehensive analysis of the solution-state aggregation behavior of poly(3-pentylthiophene) and its evolution in the blend, revealing profound impacts on film morphology and device performance. With finely optimized aggregation, the resulting all-polymer OPD achieves a record-high specific detectivity of ~4×10^13 Jones at zero bias, outperforming all bulk heterojunction (BHJ)-type self-powered OPDs reported to date. This device also demonstrates remarkable thermal stability, with negligible performance degradation after over 800 h of thermal annealing at 85 °C. Furthermore, the self-powered OPD exhibits excellent performance across a broad spectral range, enabling its application in both water quality monitoring and biosensing. This work offers new insights into the solution aggregation behavior of conjugated polymers in OPDs and highlights the importance of resolving solution aggregation in optimizing device function.