Two photovoltaic AM papers published in a single day—this team is worth watching!

　　Researcher Min Jie has long been engaged in the design and synthesis of organic optoelectronic functional materials, research on morphology, physics, and device stability, the R&D of device architectures and fabrication processes, and the industrialization of flexible batteries, with a particular focus on developing third-generation flexible organic solar-cell technology. As of May 2020, he had published more than 60 academic papers as first or corresponding author, including in journals such as Joule, Nature Communications, Energy & Environmental Science, Advanced Materials, and Angewandte Chemie. His publications have been cited over 5,000 times in Google Scholar, with an H-index of 37.

　　 1. 19.12% Efficiency! Multifunctional, Low-Cost Polymer Solar Cells Based on 4-Chlorothiazole

　　Thanks to the emergence of narrow-bandgap small-molecule acceptors (SMAs), particularly those in the “Y” series, the power conversion efficiency (PCE) of polymer solar cells (PSCs) has increased rapidly. However, with the exception of PM6 and D18, high-efficiency, easily synthesized, and broadly applicable polymer donors remain relatively scarce.
　　Min Jie and colleagues at Wuhan University, based on 4-chlorothiazole derivatives, designed and synthesized two structurally simple polymer donors, PTz3Cl and PBTTz3Cl. Compared with PTz3Cl, PBTTz3Cl exhibits slightly weaker intermolecular interactions; when blended with the SMA L8-BO, the resulting OSCs achieve a power conversion efficiency (PCE) of 18.38%. This is attributed to the stronger donor–acceptor interactions between PBTTz3Cl and L8-BO, which facilitate the formation of an optimal phase-separated morphology.
　　Further studies revealed that PBTTz3Cl exhibits excellent photovoltaic performance when paired with a wide range of small-molecule acceptors, underscoring its broad applicability. Building on this finding, ternary PSCs were designed, in which BTP-eC9 was introduced as the guest material into the PBTTz3Cl:L8-BO host system. Owing to the further optimized blend morphology and more balanced charge transport, the power conversion efficiency (PCE) was boosted to 19.12%, one of the highest values reported for PSCs. This work presents a novel design strategy for low-cost electron-deficient units, enabling the construction of highly versatile, high-performance polymer donors.

2. 18.14% Record Efficiency! Ternary All-Polymer Solar Cells Fabricated via Two-Step Sequential Deposition

　　Achieving a finely tuned active-layer morphology with appropriate vertical phase separation to enhance charge generation and transport has long been the primary goal in the pursuit of high-efficiency all-polymer bulk-heterojunction (BHJ) solar cells (all-PSCs).
　　Min Jie and colleagues at Wuhan University have proposed a solution that synergistically integrates a ternary blending strategy with the layer-by-layer (LBL) assembly process. By incorporating a highly crystalline synthetic polymer acceptor, PY-Cl, into the designed host–acceptor system PY-SSe-V, the vertical phase distribution and molecular ordering in LBL-based ternary all-PSCs can be significantly improved, outperforming those in LBL-type PM6/PY-SSe-V binary all-PSCs.
　　The formation of a high-quality bulk microstructure not only facilitates charge transport and extraction but also reduces energetic disorder and non-radiative recombination losses, thereby simultaneously enhancing all three photovoltaic parameters. Consequently, the PM6/(PY-SSe-V:PY-Cl) ternary all-PSCs achieve a maximum power conversion efficiency of 18.14%, which is among the highest values reported to date for all-PSCs. This work provides a simple and effective LBL-type ternary strategy for realizing high-efficiency all-PSCs.