Thermoelectric (TE) materials possess unique energy conversion capabilities between heat and electrical energy. Small organic semiconductors have aroused widespread attention for the fabrication of TE devices due to their advantages of low toxicity, large area, light weight, and easy fabrication. However, the low TE properties hinder their large‐scale commercial application. Herein, the basic knowledge about TE materials, including parameters affecting the TE performance and the remaining challenges of the organic thermoelectric (OTE) materials, are initially summarized in detail. Second, the optimization strategies of power factor, including the selection and design of dopants and structural modification of the dope‐host are introduced. Third, some achievements of p‐ and n‐type small molecular OTE materials are highlighted to briefly provide their future developing trend; finally, insights on the future development of OTE materials are also provided in this study.

With the great potential of the all‐polymer solar cells for large‐area wearable devices, both large‐area device efficiency and mechanical flexibility are very critical but attract limited attention. In this work, from the perspective of the polymer configurations, two types of terpolymer acceptors PYTX‐A and PYTX‐B (X = Cl or H) are developed. The configuration difference caused by the replacement of non‐conjugated units results in distinct photovoltaic performance and mechanical flexibility. Benefiting from a good match between the intrinsically slow film‐forming of the active materials and the technically slow film‐forming of the blade‐coating process, the toluene‐processed large‐area (1.21 cm2) binary device achieves a record efficiency of 14.70%. More importantly, a new parameter of efficiency stretchability factor (ESF) is proposed for the first time to comprehensively evaluate the overall device performance. PM6:PYTCl‐A and PM6:PYTCl‐B yield significantly higher ESF than PM6:PY‐IT. Further blending with non‐conjugated polymer donor PM6‐A, the best ESF of 3.12% is achieved for PM6‐A:PYTCl‐A, which is among the highest comprehensive performances.

Enhancing the built-in electric field to promote charge dynamitic process is of great significance to boost the performance of the non-fullerene organic solar cells (OSCs), which has rarely been concerned. In this work, we introduced a cheap ferroelectric polymer as an additive into the active layers of non-fullerene OSCs to improve the device performance. An additional and permanent electrical field was produced by the polarization of the ferroelectric dipoles, which can substantially enhance the built-in electric field. The promoted exciton separation, significantly accelerated charge transport, reduced the charge recombination, as well as the optimized film morphology were observed in the device, leading to a significantly improved performance of the PVDF-modified OSCs with various active layers, such as PM6 : Y6, PM6 : BTP-eC9, PM6 : IT-4F and PTB7-Th : Y6. Especially, a record efficiency of 17.72 % for PM6 : Y6-based OSC and an outstanding efficiency of 18.17 % for PM6 : BTP-eC9-based OSC were achieved.

Herein, we synthesized the first asymmetric A2-A1-D-A1-A2 type small molecule nonfullerene acceptor (NFA) by chlorination on one side of A1, namely HCl-BTA3. The synergistic effects of asymmetric structure and chlorination...

Developing robust materials is very critical and faces a big challenge for high‐performance large‐area all‐polymer solar cells (all‐PSCs) by printing methods. Herein, the authors combine the advantages of the terpolymerization strategy with the non‐conjugated backbone strategy to regulate the molecular aggregation rationally during the film‐forming printing process, facilitating a facile printing process for large‐area all‐PSCs. A series of terpolymer acceptors PYSe‐Clx (x = 0, 10, 20, and 30) is also developed, which can effectively fine‐tune the morphology and photoelectric properties of the active layer. The PBDB‐T: PYSe‐Cl20‐based all‐PSC delivers a significantly improved power cconversion efficiency (PCE) than the one with PBDB‐T: PYSe (14.21% vs 12.45%). By addition of a small amount of non‐conjugated polymer acceptor PTClo‐Y, the ternary all‐PSC reaches a PCE of 15.26%. More importantly, the regulation of molecular aggregation enables a facile blade‐coating process of the large‐area device. A record PCE of 13.81% for large‐area devices (1.21 cm2) is obtained, which is the highest value for large‐area all‐PSCs fabricated by blade‐coating. The environmentally friendly solvent processed large‐area device also obtains an excellent performance of 13.21%. This work provides a simple and effective molecular design strategy of robust materials for high‐performance large‐area all‐PSCs by a printing process.