Sequentially Solution-Deposited Active Layer: Ideal Organic Photovoltaic Device Architecture for Boron Subphthalocyanine as a Nonfullerene Acceptor

Five different solution-processed, organic photovoltaic (OPV) device architectures were screened with boron subphthalocyanine (BsubPc) as the electron acceptor paired with the PBTZT-stat-BDTT-8 polymer electron donor. These architectures include two bulk heterojunction (BHJ) devices with charge extracted in opposite directions (inverted and standard stack), a standard stack BHJ with vacuum-deposited layer on top, and two sequentially deposited planar heterojunction (PHJ) architectures. The solution–vacuum PHJ takes advantage of the ability to both solution and vacuum deposit BsubPcs with BsubPc as the acceptor layer vacuum-deposited on top of a solution-processed PBTZT-stat-BDTT-8 polymer layer. The solution–solution-mixed PHJ/BHJ represents the first example of BsubPc in a sequentially solution-deposited OPV. This architecture resulted in the best performing OPVs with a combination of high current extraction and fill factor with overall efficiency closely matching the fullerene acceptor baseline. Thus, BsubPcs in this type of architecture provides a compelling argument for BsubPcs as a replacement for fullerene-based acceptors as they are sustainable and a scalable set of chemicals. This processing method is an essential step toward large scale printing of OPVs.