• bulk heterojunction;
  • Organic photovoltaic cell;
  • Flash-photolysis time-resolved microwave conductivity;
  • Impurity effect


A correlation between the photovoltaic performance and dynamics of transient photoconductivity is investigated by flash-photolysis time-resolved microwave conductivity (FP-TRMC). This electrode-less technique offers chances to mitigate barriers for direct, speedy, and robust evaluation of bulk heterojunction (BHJ) film. We examined the blend ratio, process (solvent and thermal annealing), and impurity (a metal complex of Pd) and degradation effects in BHJ films consisting of poly(3-hexylthiophene) (P3HT) and methanofullerene (PCBM). The minimum charge carrier mobility of 0.22 cm2V−1s−1 was found in P3HT:PCBM = 1:1 film along with 3.26% power conversion efficiency. The revealed good correlation is not only applicable to process optimization, but also expected as a facile screening method to survey the potential of optoelectronic materials.