Selenization Strategy of Phenazine‐based Non‐Fullerene Acceptors Promotes Photon Harvesting and Reduces Voltage Loss in Organic Solar Cells

Abstract

Phenazine‐based small molecular acceptors (SMAs), which benefit from the reduced energy loss (Eloss), have emerged as promising candidates for achieving high‐efficiency organic solar cells (OSCs). Nevertheless, the potential advancements of phenazine‐based photovoltaic devices are hindered by the constrained short‐circuit current (Jsc). Though the incorporation of selenium (Se) atoms has been proven effective in enhancing Jsc, it simultaneously introduces molecular disorder stacking and charge recombination. Based on the desire to harness the full potential of phenazine structure and the benefits of Se substitution, a series of Se‐substituted phenazine‐based SMAs, namely PzIC‐SSe‐4F and PzIC‐SeSe‐4F are meticulously synthesized. Due to the increased photon harvesting capabilities, the photovoltaic device using PzIC‐SeSe‐4F demonstrated a significantly increased Jsc of 27.73 mA cm−2. Remarkably, the PzIC‐SeSe‐4F‐based device displayed an astonishing open circuit voltage (Voc) of 0.873 V, representing the highest Voc recorded among all reported symmetric Se‐substituted Y‐series SMAs‐based photovoltaic devices. Thanks to the synergistic effect of phenazine central cores and Se substitution, the PM6:PzIC‐SeSe‐4F‐based device achieves a power conversion efficiency (PCE) of 17.69%. The findings serve as a pivotal reference for further development of high‐efficiency Se‐substituted photovoltaic devices.