Self-Organized Discotic Liquid Crystals for High-Efficiency Organic Photovoltaics

TLDR

Solution‑processed liquid crystalline conjugated materials can self‑assemble into thin films with photodiode‑optimized structures. By combining hexabenzocoronene and perylene in a discotic liquid crystal, the authors create vertically segregated thin films that enable efficient photoinduced charge transfer and charge transport. These films deliver external quantum efficiencies exceeding 34 % at 490 nm, demonstrating that simple solution‑processing can produce inexpensive, high‑performance thin‑film photovoltaics.

Abstract

Self-organization of liquid crystalline and crystalline-conjugated materials has been used to create, directly from solution, thin films with structures optimized for use in photodiodes. The discotic liquid crystal hexa-peri-hexabenzocoronene was used in combination with a perylene dye to produce thin films with vertically segregated perylene and hexabenzocoronene, with large interfacial surface area. When incorporated into diode structures, these films show photovoltaic response with external quantum efficiencies of more than 34 percent near 490 nanometers. These efficiencies result from efficient photoinduced charge transfer between the hexabenzocoronene and perylene, as well as from effective transport of charges through vertically segregated perylene and hexabenzocoronene π systems. This development demonstrates that complex structures can be engineered from novel materials by means of simple solution-processing steps and may enable inexpensive, high-performance, thin-film photovoltaic technology.