Mechanisms controlling the efficiency of polymer solar cells

To improve the efficiency of polymer solar cells, it is vital to understand which mechanisms control the current-voltage characteristics of a given device. Temperature and light intensity dependence of the main solar cell parameters are very informative for analyzing losses. We report on the current-voltage characteristics and the external photogeneration quantum yield of ITO/PEDOT:PSS/OC1C10-PPV:PCBM/Al as well as of ITO/PEDOT:PSS/P3HT:PCBM/Al devices investigated in the broad temperature range 120-325 K under variable illumination, between 0.02 and 100 mW/cm(2). We discuss the recombination on traps and the low mobility of charge carriers caused by poor morphology of active layers as possible mechanisms limiting the efficiency of these devices.