Open-circuit voltage enhancement of inverted polymer bulk heterojunction solar cells by doping NaYF4nanoparticles/PVP composites

Abstract

NaYF₄ nanoparticles (NPs) were synthesized by a facile solvothermal approach using polyvinylpyrrolidone (PVP) as a surfactant. The NPs were doped into P3HT:PCBM blend to fabricate inverted polymer bulk heterojunction (BHJ) solar cells. The dependence of device performance on the weight ratio of NPs in the blend film was investigated. The results showed that the open-circuit voltage was apparently enhanced by doping NaYF₄ NPs/PVP composites into the active layer while maintaining the short-circuit current density and fill factor, leading to an increase in power conversion efficiency. The results of cyclic voltammetry measurement revealed that PVP had a deeper HOMO energy level than that of P3HT. PVP carried by NPs might also form charge transfer (CT) complexes with PCBM, which can make contributions to the open-circuit voltage. The study of photoluminescence (PL) spectra indicated clear evidence for enhanced exciton dissociation and reduced charge recombination in the blend film with NPs.