The improved efficiency of low molecular weight organic solar cells doped with a Cu(I) triplet material

Abstract

We developed a method to improve the performance of the copper phthalocyanine (CuPc)/fullerene (C₆₀) organic solar cells (OSCs) by doping CuPc with a long triplet lifetime material. By doping [Cu(bis[2-(diphenylphosphino)phenyl]ether)(benzo[i]dipyrido[3,2-a:2′,3′-c]phenazine)]BF₄ (CuDB) into CuPc, the enhanced short-circuit current density (J_SC) of 6.213 mA/cm², open-circuit voltage (V_OC) of 0.39 V and a peak power conversion efficiency (PCE) of 0.92% compared to 0.79% of the standard CuPc/C₆₀ OSCs are achieved under 1 sun AM 1.5 G illumination at an intensity of 100 mW/cm². The performance improvement is mainly attributed to the long triplet lifetime of CuDB (τ = 70.05 μs) which leads to more effective exciton dissociation.