Dispersive transport in the temperature dependent transient photoresponse of organic photodiodes and solar cells

作者：Christ Nico^*; Kettlitz Siegfried; Mescher Jan; Valouch Sebastian; Lemmer Uli

来源：Journal of Applied Physics, 2013, 113(23): 234503.

DOI：10.1063/1.4810897

The nanosecond transient photoresponse of organic solar cells and photodiodes based on a conjugated polymer (poly(3-hexylthiophene-2,5-diyl)) blended with a fullerene derivative ([6,6]-phenyl C-61-butyric acid methyl ester) exhibits a strong temperature dependence, whose origin can be traced back to charge carrier transport phenomena. In the framework of a drift-diffusion model including multiple-trapping, the temperature dependence of effective mobilities arises naturally without the need of using a temperature dependent parameterization of the mobilities. Furthermore, the extended drift-diffusion simulation reproduces the measured change of slope of the transient current density from j(t) similar to t((-1+alpha)) to j(t) similar to t((-1-alpha)), indicating dispersive charge carrier transport influenced by an exponential trap distribution characterized by the dimensionless parameter alpha. A second kink is identified to be the point in time of the crossover from electron to hole dominated charge carrier transport, enabling for the determination of the donor and acceptor transport properties independent of each other.

• 出版日期2013-6-21