Effect of the Selective Halogenation of Small Molecule Acceptors on the Blend Morphology and Voltage Loss of High‐Performance Solar Cells. (19th March 2022)

• Record Type: Journal Article
• Authors: Kim, Geon‐U; Sun, Cheng; Lee, Dongchan; Choi, Gi‐Seok; Park, Jin Su; Seo, Soodeok; Lee, Seungjin; Choi, Do‐Yeong; Kwon, Soon‐Ki; Cho, Shinuk; Kim, Yun‐Hi; Kim, Bumjoon J.
• Is Part Of: Advanced functional materials. Volume 32:Number 25(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-03-19
• Subjects: blend morphology -- halogenation -- organic solar cells -- small molecule acceptors -- voltage loss; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.202201150
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: Herein, the impacts of the selective halogenation at two different positions of dicyanomethylene‐3‐indanone (IC) end groups and inner side chains of small molecular acceptors (SMAs) on the P D :SMA interfacial interactions, blend morphology, and resulting photovoltaic properties are described. In this study, four different SMAs (A1, A2, A3, and A4) with the same molecular backbone, but with different degrees of halogenation, are synthesized. The IC end groups on the backbones of the A1 and A3, and A2 and A4 SMAs are chlorinated and fluorinated, respectively; in addition, 6‐phenoxyhexyl inner side chains of the A3 and A4 are chlorinated. The SMAs are paired with a chlorinated PBDT‐Cl P D to construct organic solar cells (OSCs). The PBDT‐Cl:A4‐based OSC exhibits the highest power conversion efficiency of 17.2%, outperforming the PBDT‐Cl:A1‐(13.3%), PBDT‐Cl:A2‐(15.6%), and PBDT‐Cl:A3‐based OSC (16.5%). The Cl atoms on the side chains in the A3 and A4 SMAs enhance the molecular/energetic interactions at the P D :SMA interfaces and improve the blend morphology in terms of domain purity and spacing. These effects lead to the improved fill factors and reduced voltage loss of the PBDT‐Cl:A3‐ and PBDT‐Cl:A4‐based OSCs. This study demonstrates the importance of appropriate halogenation of SMAs in optimizing the blend morphology, reducing voltage loss, and improving OSC performance. Abstract : This paper describes the impacts of sequential halogenation in selective positions of small molecule acceptors on the blend morphology, voltage loss, and photovoltaic performances. The A4‐based organic solar cells exhibit the highest power conversion efficiency of 17.2%, attributed to the optimized blend morphology and reduced voltage loss.