Boosting the Long-Term Stability of All-Polymer Solar Cells by Using Natural Cellulose as Interlayer

Abstract

We conducted a thorough evaluation of the durability issues associated with organic/inorganic interfaces in inverted all-polymer solar cells (All-PSCs) and systematically investigated various interlayers, including polyethyleneimine (PEI), polyethylenimine ethoxylated (PEIE), and natural cellulose. Our findings reveal that natural cellulose stands out due to its exceptional water resistance, high adsorption energy, strong hydrogen bonding with ZnO, and a morphology that effectively prevents water molecules from penetrating the ZnO surface. Consequently, ZnO/cellulose device retains 80% of its initial power conversion efficiency (T80 lifetime) for 2,030 hours under humid aging conditions at 25°C and 40% relative humidity (RH). Moreover, cellulose exhibits excellent interfacial compatibility with both the active layer and ZnO, leading to an impressive T80 lifetime of 2,712 hours under thermal aging at 75°C in N2. The ZnO/cellulose device also demonstrates remarkable resilience under harsher conditions, maintaining a T80 lifetime of 572 hours when stored at 75°C and 50–60% RH. This study presents a sustainable and eco-friendly strategy to significantly enhance the long-term stability of All-PSCs.