Solution-processed fullerene interlayer for organic-inorganic hybrid solar cells

Organic-inorganic hybrid solar cells as low-cost renewable energy sources have attracted great attention due to the possibility of fabricating them on large-area, light-weight, flexible substrates by printing and coating technologies. Hashimoto et al. investigated the performance dependence of poly(3-hexylthiophene) (P3HT): (6,6)-phenyl C₆₁ butyric acid methyl ester (PCBM)/ZnO hybrid solar cells on the length of the ZnO nanorods and reported a PCE up to 2.7 %. However, compared to the polymer solar cells, the hybrid solar cells tend to have lower PCEs due to poor electrical coherence at the organic/inorganic interface. One approach to solve this issue is to modify the organic/inorganic interface with a functional interlayer. However, few studies focus on solution-processed interlayer for hybrid solar cells with ZnO nanorod arrays. In this paper, a solution-processed fullerene interlayer at the P3HT:PCBM/ZnO interface is introduced to improve the photovoltaic performance. Compared to vacuum process for most interlayer, the solution process offers the advantage of low cost.