Almost all of the high efficiencies of all-polymer solar cells (all-PSCs) are obtained using chloroform as the solvent. Sequential processing and a ternary strategy are combined to enable the highest efficiency, 18.1%, for all-PSCs processed from an aromatic hydrocarbon solvent, which is also comparable to the highest value processed from chloroform.
Abstract
All-polymer solar cells (all-PSCs) have promising potential for industrial production due to their superior stability. Recently, the widespread application of the polymerized small molecule acceptor (PSMA) has led to a surge in the efficiency of all-PSCs. However, the high efficiencies of these devices generally rely on the use of the highly volatile solvent, chloroform (CF). Furthermore, the molecular weights of PSMA are lower than polymer donors, yet their crystallinity is weaker than typical small molecules, making most PSMA-based all-PSCs suffer from low electron mobility. To improve device performance and facilitate large scale production of all-PSCs, it is necessary to enhance electron mobility and avoid the use of CF. This paper investigates the use of sequential processing (SqP) for active layer preparation using toluene as the solvent to address these issues. This work reports 18.1% efficient all-PSC devices, which is the highest efficiency of all-PSCs prepared using non-halogen solvents. This work systematically compares the conventional blend-casting method with the SqP method using PM6 as the donor and PY-V-γ and PJ1-γ as the acceptors, and compares the performance of binary and ternary blends in both methods. Finally, this work measures the device stability and finds that SqP can significantly improve the photostability of the device.
