The cost‐effectiveness of polymer solar cells is a very important concern for future applications. In this work, a new combinatory side chain integrating siloxane terminal and alkoxy group is developed, and three polymers, PQSi05, PQSi10, and PQSi25, with 5%, 10%, and 25% contents of the siloxane‐terminated alkoxy side chain, respectively, are successfully synthesized. As the content of the combinatory side chain increases, the surface energy of the corresponding polymer film decreases, showing tunable miscibility in blend films with nonfullerene acceptor IT‐4F. A maximum power conversion efficiency (PCE) of 13.56% is achieved in the PQSi05:IT‐4F‐based device. The minor (5%) combinatory side chain approach retains a low synthetic complexity (SC) of 16.58% for PQSi05. Due to the improved device performance, a low figure‐of‐merit (FOM) of 1.22 is obtained for the PQSi05:IT‐4F blend. Furthermore, the contribution of the IT‐4F acceptor is considered for a comprehensive analysis, yielding an average SC (ASC) of 39.31% and an average FOM (AFOM) of 2.90. After statistical analyses and calculations, the PQSi05:IT‐4F is the best cost‐effective active layer to date. It is revealed that the introduction of the minor combinatory side chain is a promising strategy to develop high‐performing and cost‐effective polymer donors.

Molecular orientation in polymer solar cells (PSCs) is a critical subject of investigation that promotes the quality of bulk heterojunction morphology and power conversion efficiency (PCE). Herein, the intrinsic polymer orientation transition can be found upon delicate control over the branching point position of the irregular alkoxy side chain in difluoroquinoxaline−thiophene-based conjugated polymers. Three polymers with branching points at the third, fourth, and fifth positions away from the backbone were synthesized and abbreviated as PHT3, PHT4, and PHT5, respectively. Temperature-dependent absorption behavior manifests the polymer aggregation ability in the order of PHT3 < PHT4 < PHT5. Surprisingly, the polymer orientation transition from typical face-on to edgeon emerged between PHT4 and PHT5, as evidenced by X-ray-scattering analysis. The enhanced face-on crystallinity of PHT4 endowed the o-xyleneprocessed PHT4:IT-4Cl-based devices with the highest PCE of 13.40%. For PHT5 with stronger aggregation, the related o-xylene-processed PSCs still showed a good PCE of 12.66%. Our results demonstrate that a delicate polymer orientation transition could be realized through a precisely controlled strategy of the side chain, yielding green-solvent-processed high-performance PSCs.

The efficient as-cast polymer solar cells being processed by the non-halogenated solvent are capable for the roll-to-roll printing technique. Herein, three dithienobenzoxadiazole-based wide bandgap polymers PBOffDT, PBOTT and PBOTVT, which...

A binary solvent approach simultaneously improves the open-circuit voltage, short-circuit current, and fill factor, and finally elevates the as-cast photovoltaic performance.