Recent Advances in Y6‐Based Semiconductors: Performance in Solar Cells, Crystallography, and Electronic Structure

Abstract

The advent of crescent-shaped Y6 and its derivatives have recently enabled exceptionally high solar cell performance metrics, for structural, physical, and transport characteristics that remain poorly understood. Here we summarize recent progress on crystallography, electronic structure, and device performance of this kind of non-fullerene acceptors. First, we discuss molecular engineering and the crystal structure of Y6 and its derivatives. Second, we present theoretical modeling of the molecular orbitals, reorganization energy, and electronic couplings. Third, we summarize single carrier diode and solar cell performance, and discuss the correlations between crystal structure and computational insights. Finally, we discuss unsolved problems and future developments in this field. Overall, this Minireview summarizes crystal structure, computational understanding, and device metrics, thus providing an outlook for future organic semiconductors design and mechanistic studies in fundamental research and industrial applications.

Slip‐Stacked J‐Aggregate Materials for Organic Solar Cells and Photodetectors

“…Initially ADA7 ( Y6 ) was demonstrated in OSC by Zou and co‐workers in 2019, reaching 15.7% PCE in a BHJ OSC with polymer PBDB‐TF ( PM6 ) as donor material. [ 120 ] Ever since, ADA7 ( Y6 ) has received a considerable amount of research interest within the OSC community [ 121 ] and has been used to fabricate the highest efficiency small‐molecule acceptor‐based BHJ OSCs to‐date with PCE of > 18% with donor polymer D18 . [ 57 ] ADA7 ( Y6 ) hereby consists of a dithienothiophenepyrrolobenzothiadiazole D‐A'‐D core with fluorinated DCIND terminal acceptor moieties, effectively making it an A‐D‐A'‐D‐A‐type acceptor in a dipolar cisoid conformation.…”

Impact of substituents on the performance of small-molecule semiconductors in organic photovoltaic devices via regulating morphology

“…The report of Y6 (Fig. 10b) by Yuan et al 142 in 2019, which demonstrated an excellent PCE of 15.7% with the PM6:Y6 BHJ OPV, brought about the development of this class of molecules, 143 and optimization of peripheral substituents has been an important part of the research as in the case of other SMSCs. This section reviews relevant papers on this topic.…”

Vertical Distribution in Inverted Nonfullerene Polymer Solar Cells by Layer‐by‐Layer Solution Fabrication Process

“…Although PCEs over 18% have been realized, the PM6:Y6 system, as being the bench mark device with PCE over 15%, is still the best protocol for investigating the morphology research, device mechanism, and fabrication optimization because most highperformance donors and acceptors are the derivatives of PM6 and Y6, respectively. [24][25][26] Furthermore, PM6:Y6 system has been successfully used in several LBL-based work, [27,28] such as largescale protocol and semitransparent devices. [29,30] Herein, LBL-processed PSCs with inverted structure are fabricated with polymer PM6 as the electron donor and the nonfullerene small molecule Y6 as the electron acceptor.…”