Performance enhancement in organic-inorganic hybrid photovoltaic cells by adding a carbon-nanostructure interface layer

Inverted photovoltaic configuration overcomes the stability problem in conventional polymer photovoltaic device. However, the charge transport property at the organic-inorganic junctions is one of the important issues affecting the performance of this type of photovoltaic cells. To solve the problem, we deposit a carbon-nanostructure layer, C₆₀, on the inorganic ZnO-nanorod array surface to be in contact with a polymer blend, poly(3-hexylthiophene):(6,6)-phenyl C₆₁ butyric acid methyl ester (P3HT:PCBM), forming a ZnO/C₆₀/P3HT:PCBM/Ag device. In the presence of the C₆₀ layer, both the short circuit current (J_SC) and open circuit voltages (V_OC) are improved leading to an enhancement in the power conversion efficiency from 1.3% to 2.1%. The role of the C₆₀ layer is to assist the exciton separation and transport the electrons to the collecting electrode.