Evaporation-Free Nonfullerene Flexible Organic Solar Cell Modules Manufactured by An All-Solution Process

To ensure laboratory-to-industry transfer of next-generation energy harvesting organic solar cells (OSCs), it is necessary to develop flexible OSC modules that can be produced on a continuous roll-to-roll basis and to apply an all-solution process. In this study, nonfullerene acceptors (NFAs)-based donor polymer, SMD2, is newly designed and synthesized to continuously fabricate high-performance flexible OSC modules. Also, multifunctional hole transport layers (HTLs), WO3/HTL solar bilayer HTLs, are developed and applied via an all-solution process called ProcessOne into inverted structure. SMD2, the donor terpolymer, has a deep highest occupied molecular orbital (HOMO) level and can achieve a power conversion efficiency (PCE) of 11.3% with NFAs without any pre-/post-treatment because of its optimal balance between crystallinity and miscibility. Furthermore, the integration of multifunctional HTLs enables the recovery of the drop in open circuit voltage (V-OC) caused by a mismatch in energy levels between the deep HOMO level of the NFAs-based bulk-heterojunction layer and the solution-processed HTLs. Also, the photostability under ultraviolet-exposure necessary for ProcessOne is greatly improved because of the integration of multifunctional HTLs. Consequently, because of the synergistic effects of these approaches, the flexible OSC modules fabricated in an industrial production line have a PCE of 5.25% (P-max = 419.6 mW) on an active area of 80 cm(2).