Study of Charge Carrier Dynamics of P3HT:PCBM Blend for Active Material Solar Cell Using Muon Spin Relaxation

Abstract

Poly (3-hexylthiohene) (P3HT) has attracted much attention due to their chemical and thermal stability as well as their potential to be used as an active material in solar cells. Recently, bulk-heterojunction BHJ solar cell has been intensively developed due to its potential for high power conversion efficiency and low cost solar cells. Many studies have been done to understand the effect of PCBM to the morphology of the P3HT:PCBM blend and to performance of its solar cells. However, the clearly explanation about the effect of PCBM to the charge carrier dynamics in P3HT is not well understood yet. We have studied charge carrier dynamics in active material of solar cell P3HT:PCBM along and perpendicular to the chain by means of longitudinal field (LF) muon-spin-relaxation (μSR) method to elucidate the intra and inter-chain charge carrier in polymer hybrid P3HT:PCBM. We found the charge carrier transport changes from intra-chain to inter-chain diffusion. One dimensional intra-chain diffusion is observed in the samples at low temperatures below 10K, while three dimensional inter-chain is observed at high temperatures above 15K. This temperature is lower than that of P3HT only.