Minimized optical/electrical energy loss for 25.1% Monolithic perovskite/organic tandem solar cells

Perovskite/organic tandem solar cells (PO-TSCs) exploit the advantages of cost-effective fabrication, orthogonal solvent processing for perovskite and organic absorber layers, and compatibility with low-temperature, high-throughput deposition techniques. However, their performance remains hampered by energy losses of subcells and interconnecting layers (ICLs). Here, an energy loss management strategy for PO-TSCs is proposed, focusing on the simultaneous regulation of defect states in perovskite front subcells and the reduction of optical and electrical losses in the ICL. The synergistic effect of hydrogen bonding and coordination interactions between the pyridinium bromide perbromide and perovskite layer effectively mitigates ion migration, thereby minimizing energy losses. Meanwhile, the optimized V2O5-based ICL structure not only demonstrates excellent transmissivity for near-infrared photons but also allows for barrier-free extraction of charge carriers. Such structure can provide a low-loss interface, facilitating light management within the bulk heterojunction, which effectively balances the current between the front and rear subcells. Taken together, the resulting PO-TSCs deliver a power conversion efficiency of 25.1% with a high open-circuit voltage of 2.10 V. The performance of perovskite/organic tandem solar cells remains hampered by the energy losses of subcells and interconnecting layers (ICLs). Here, authors introduce pyridinium bromide perbromide into perovskites and employ a V2O5-based ICL, achieving a maximum efficiency of 25.1% in tandem devices.