Processing solvent, weight fraction of [6,6]-phenyl C61-butyric acid methyl ester, and molecular weight of poly(3-hexylthiophene) dependences : Charge transporting studies of P3HT/PCBM bulk heterojunction photovoltaics

In this letter, we presents an investigation of hole and electron transport properties in P3HT:PCBM (1:0.8) blends prepared with different solvents (chlorobenzene, 1,2-dichlorobenzene, toluene, and o-xylene) using time-of-flight (TOF) photocurrent measurements. The analysis of the extracted charge mobilities reveals the solvent dependence in the preparation of the polymer blends on the formation of conducting networks. The TOF mobility measurement provides a probe of the interpenetrating networks within the polymer blends under different preparation conditions (annealing time and temperature, solvent, etc.). The TOF method has also been used to study the effect of weight fractions of PCBM in the blend film and P3HT molecular weight on charge mobility in polymer/fullerene solar cells.