Enhancement of the power conversion efficiency in a polymer solar cell using a work-function-controlled TimSinOx interlayer

Abstract

Work-function-adjustable Ti_mSi_nO_x provides an opportunity to optimize the energy-level alignment at the photoactive/cathode interface in the polymer bulk heterojunction solar cell. The work function of Ti_mSi_nO_x is engineered by adjusting the Si mol% during the sol–gel reaction. The controlled work function provides an energetically downhill cascade pathway for electrons from the electron acceptor to the cathode, which contributes to improvement in electron collection at the cathode. The valence band maxima of Ti_mSi_nO_x also become deeper as the Si mol% increases and the hole-blocking ability of Ti_mSi_nO_x is enhanced as a result. Accordingly, polymer solar cells fitted with the optimized Ti_mSi_nO_x exhibit enhanced performance.