Effect of Thermal Stress on Power Conversion Efficiency of PCDTBT: PC_(71)BM Organic Solar Cells

摘要

The effect of thermal stress on poly[N-900-hepta-decanyl-2,7-carbazole-alt-5,5-(40,70-di-2-thienyl-20,10,30-benzothiadiazole)] (PCDTBT): [6,6]-phenyl C_(71)-butyric acid methyl ester (PC_(71) BM) composite films based organic solar cells has been examined. The optical absorption spectra of PCDTBT:PC_(71)BM composite shows that absorption remains almost unchanged till ~ 150 °C. However, the absorption peak falls by more than 30% for the film annealed at 200 °C. It has also been observed that photoluminescence (PL) of the PCDTBT:PC_(71)BM composite films is best quenched by an order of magnitude at an annealing temperature of 150 °C showing a significant transfer of electrons from donor to acceptor. The maximum photo conversion efficiency (PCE) of the solar cell has been found to increase significantly (from 0.51 to~2.25%) for sample annealed at 150 °C and beyond that it starts decreasing.