A theoretical comparison of different third component content in ternary organic solar cells

Abstract

Ternary solar cells have been rapidly developed in the realm of organic solar cells (OSCs). The incorporation of a third component into a cell results in a complicated active layer morphology, and the relation of this morphology to power conversion efficiency remains elusive. In this work, two ternary active layers, B1:Y7 (10 wt%):BO-4Cl and B1:Y7 (50 wt%):BO-4Cl are constructed, and the reasons for the differences in PCE caused by varying the Y7 content are investigated using theoretical calculations. Firstly, four groups of binary complexes (B1:BO-4Cl-10 wt%, B1:BO-4Cl-50 wt%, B1:Y7-10 wt%, B1:Y7-50 wt%) were examined using molecular dynamics simulation and the stacking patterns of the complexes could mainly be categorized into three groups (IC-T, IC-BDT, IC-RHD). The results showed that with an increase of the Y7 content, the proportion of IC-T stacking decreased while IC-BDT stacking increased. Moreover, the properties of each stacking pattern were calculated and IC-T stacking was found to have a greater charge separation coupling and rate, and a smaller interaction energy. With more IC-T stacking, the number of charge transfer (CT) states and CT mechanisms in B1:BO-4Cl-10 wt% and B1:Y7-10 wt% improves the PCE of B1:Y7 (10 wt%):BO-4Cl. For the trimers, a greater number of CT states and CT pathways can also facilitate efficient charge separation in B1:Y7 (10 wt%):BO-4Cl. Additionally, this work provides basic knowledge of the influence that the third component content on cell performance, providing theoretical instruction for experimental work based on Y-series non-fullerene acceptor materials.