Crystallinity and Molecular Packing of Small Molecules in Bulk-Heterojunction Organic Solar Cells

Emilio Palomares (1) , Laurent Billon (1) , Aurelien Viterisi (1)

1 IPREM - Institut des sciences analytiques et de physico-chimie pour l'environnement et les materiaux

Crystallinity has played a major role in organic solar cells (OSCs). In small molecule (SM) bulk-heterojunction (BHJ) OSCs, the crystallinity and crystalline packing of SM donors have been shown to have a dramatic impact on the formation of an optimum microstructure leading to high-power conversion efficiency (PCE). Herein we describe how crystallinity differs from polymers to SMs, and how the packing habits of SMs (particularly donors) in active layers of BHJ devices can be described as following two different main modes: a single crystal-like and a liquid crystal-like packing type. This notion is reviewed from a chronological perspective, emphasising milestone donor structures and studies focusing on the crystallinity in SM-BHJ OSCs. This review intends to demonstrate that a shift towards a liquid crystalline-like packing can be identified throughout the history of SM-BHJ, and that this shift can be associated with an increase in overall PCE

Keywords: organic solar cell; photovoltaics; small molecule; bulk heterojunction; crystallinity; crystalline packing

Domains: Chemical Sciences; Polymers

Emilio Palomares, Laurent Billon, Aurelien Viterisi. Crystallinity and Molecular Packing of Small Molecules in Bulk-Heterojunction Organic Solar Cells. Applied Sciences, 2022, 12 (11), pp.5683. ⟨10.3390/app12115683⟩. ⟨hal-03767013⟩