Charge carrier transport in blend of P3HT and ZnO nanoparticles at low temperature studied by μsR

Recently, hybrid solar cell, which is a combination of organic and inorganic material, has been developed to produce better performance especially in power conversion efficiency of solar cell. Organic material based on conjugated polymer such as Poly(3-hexylthiophene) (P3HT) attracted much attention because P3HT shows the highest hole mobility among the series of Poly(3-alkylthiophene). On the other hand, it is well known that ZnO nanoparticles are an inorganic material with high electron mobility that can be acted as electron acceptor to dissociate excitons formed in organic material. The existence of ZnO nanoparticles in active layer of solar cell will lead to dissociation of excitons in P3HT via rapid electron transfer to ZnO. To understand the mechanism of charge carrier transport in blend of P3HT and ZnO nanoparticles, we have been conducted an experiment using muon spin relaxation (μSR) at low temperature of 10 K with variation of longitudinal field from 2 to 395 mT. We also investigated the effect of light irradiation to the charge carrier transport in blend of P3HT and ZnO nanoparticles. Without light irradiation, it is clearly observed that depolarization rate (λ) was proportional to linier field of H^-0.5, indicating one-dimensional intra-chain transport of charge carrier. With light irradiation, it is found that asymmetry data changed slightly indicating the trace of any changing of charge carrier transport to increase in the amount of exciton in samples causing by light irradiation.