Process‐Aid Solid Engineering Triggers Delicately Modulation of Y‐Series Non‐Fullerene Acceptor for Efficient Organic Solar Cells

• Published in: Advanced materials (Weinheim) Vol. 34; no. 20; pp. e2200907 - n/a
• Main Authors: Song, Xin, Zhang, Kai, Guo, Renjun, Sun, Kun, Zhou, Zhongxin, Huang, Shenglei, Huber, Linus, Reus, Manuel, Zhou, Jungui, Schwartzkopf, Matthias, Roth, Stephan V., Liu, Wenzhu, Liu, Yu, Zhu, Weiguo, Müller‐Buschbaum, Peter
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01-05-2022
• Subjects: asymmetric configuration; Asymmetric configurations; Asymmetry; Cell engineering; Charge efficiency; Charge transport; Chlorobenzene; Component distributions; Dipole moments; Efficiency; Energy conversion efficiency; Exciton splitting; Excitons; Geometry; Materials science; Maximum power; Molecules; organic solar cells; Phase separation; Photovoltaic cells; Power conversion efficiencies; Process aid; Solar cells; Solids engineering; Splitting; Symmetrics; Thick films; Thickness; Thickness tolerance; volatile solid; Y-series molecule; Y-series molecules; organic solar cells; thickness-tolerance; volatile solid; asymmetric configuration; Y-series molecules
• ISSN: 0935-9648; 1521-4095; 1521-4095
• DOI: 10.1002/adma.202200907

Volatile solids with symmetric π‐backbone are intensively implemented on manipulating the nanomorphology for improving the operability and stability of organic solar cells. However, due to the isotropic stacking, the announced solids with symmetric geometry cannot modify the microscopic phase separation and component distribution collaboratively, which will constrain the promotion of exciton splitting and charge collection efficiency. Inspired by the superiorities of asymmetric configuration, a novel process‐aid solid (PAS) engineering is proposed. By coupling with BTP core unit in Y‐series molecule, an asymmetric, volatile 1,3‐dibromo‐5‐chlorobenzene solid can induce the anisotropic dipole direction, elevated dipole moment, and interlaminar interaction spontaneously. Due to the synergetic effects on the favorable phase separation and desired component distribution, the PAS‐treated devices feature the evident improvement of exciton splitting, charge transport, and collection, accompanied by the suppressed trap‐assisted recombination. Consequently, an impressive fill factor of 80.2% with maximum power conversion efficiency (PCE) of 18.5% in the PAS‐treated device is achieved. More strikingly, the PAS‐treated devices demonstrate a promising thickness‐tolerance character, where a record PCE of 17.0% is yielded in PAS devices with a 300 nm thickness photoactive layer, which represents the highest PCE for thick‐film organic solar cells.
A low‐cost, high volatile, and asymmetric halogen benzene derivate, 1,3‐dibromo‐5‐chlorobenzene, is applied as process‐aid solid to manipulate the blend nanomorphology and enhance the crystallinity in Y‐series small molecule‐based photoactive layer system. A champion power conversion efficiency of 17.0% is yielded, which is one of the highest performances for thick‐film organic solar cells.