End Group Effect of Asymmetric Benzodithiophene‐Based Donor with Liquid‐Crystal State for Small‐Molecule Binary Solar Cell. Issue 6 (27th November 2022)

• Record Type: Journal Article
• Authors: Zhao, Yong; Huang, Ziwei; Kang, Xiao; Yu, Jifa; Ding, Minggeng; Liu, Deyu; Lu, Guanghao; Bao, Xichang; Yu, Liangmin; Sun, Mingliang
• Is Part Of: Small. Volume 19:Issue 6(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-11-27
• Subjects: asymmetry -- liquid crystals -- organic solar cells -- small molecule donors; Nanotechnology -- Periodicals; Nanoparticles -- Periodicals; Microtechnology -- Periodicals; 620.5
• DOI: 10.1002/smll.202205244
• Languages: English
• ISSNs: 1613-6810

Abstract

Abstract: Liquid‐crystal small molecule donor (LC‐SMD) is a new type organic semiconductor, which is attractive not only for the easy synthesis and purification, well‐defined chemical structures, etc., but also for the LC state that makes the crystallinity and aggregation state of molecules adjustable. Here, one new LC‐SMD ( a ‐BTR‐H4) is synthesized with 1D alkoxyl and 2D thiophene‐alkylthiol side‐chained benzo[1, 2‐ b :4, 5‐ b ′]dithiophene core, trithiophene π‐bridge, and 3‐(2‐ethylhexyl) rhodanine end group. a ‐BTR‐H4 shows low LC transition temperature, 117 °C, however, counterpart material ( a ‐BTR‐H5) with the same main structure but 3‐ethyl rhodanine terminal group does not show LC properties. Although a ‐BTR‐H4/H5 show similar Ultraviolet–visible absorption spectrum and energy levels, a ‐BTR‐H4 affords relatively high photovoltaic performances due to favorable blend morphology produced by the consistent annealing temperature of Y6‐based accepters and liquid crystal temperature of donors. Preliminary results indicate that a ‐BTR‐H4 gains a power conversion efficiency (PCE) of 11.36% for Y6‐based devices, which is ascribed to better light harvest as well as balanced carrier generation and transport, while a ‐BTR‐H5 obtains 7.57% PCE. Therefore, some materials with unique nematic LC phase have great application potential in organic electronics, and further work to utilize a ‐BTR‐H4 for high‐performance device is underway. Abstract : One new small molecule donor with the combination strategy of symmetry‐breaking and liquid‐crystal (LC) property is synthesized. The LC temperature (117 °C) of a ‐BTR‐H4 coincides well with the thermal annealing temperature of Y6‐based accepters, which is conducive to gaining more favored morphology, better light harvest as well as balanced carrier generation and transport in binary all‐small‐molecule‐organic solar cells.