Charge Carrier Dynamics in Planar Heterojunction Organic Solar Cells

• DOI: 10.1002/solr.202300267
• Publication Date: 2023-04-18T11:59:35Z
• Authors: Yexiao Huang; Sein Chung; Safakath Karuthedath; Catherine S. P. D...; Hua Tang; Minyoung Jeong; Shirong Lu; Kilwon Cho; Frédéric Laquai; Zhipeng Kan
• Keywords: Acceptor; Charge carrier; Band offset

The ionization energy (IE) offset of a donor–acceptor pair provides the driving force for hole transfer and subsequent free charge carrier generation in low‐bandgap nonfullerene organic solar cells (OSCs). However, interfacial energetic landscape bulk heterojunction OSCs is determined by materials’ electronic structure intermolecular interactions at donor/acceptor interface, causing local energy‐level shifts disorder. Herein, impact IE on efficiency dynamics systematically evaluated characterizing PM6/ITIC, PM6/IT‐2Cl, PM6/IT‐4Cl planar (PHJ) cells. Ultrafast spectroscopy time‐resolved density measurements reveal that an about ≈0.5 eV leads to efficient generation. Furthermore, bimolecular recombination consequently triplet are significantly reduced systems with high offset. This work underlines importance sizeable offsets PHJ as critical high‐efficiency material device design.