Abstract

Simultaneous transient absorption and transient photovoltage/photocurrent studies on complete P3HT /PCBM solar cells allows measurement of the field dependence of transport, charge mobility, and charge recombination in the blend layer. Because the transient absorption measurements are done by reflection of the probe beam off the aluminum electrode we do optical and electrical characterization of the same device. Analogous studies on liquid-junction and solid-state dye-sensitized cells allow us to compare the differing contributions of drift and diffusion to both transport and recombination across the three main types of “bulk heterojunction” cells. We find evidence for a contribution of electric field to the charge transport in the solid-state dye cells. Additional temperature dependence studies allow measurement of activation energies which illuminates the contribution of trapping and detrapping to all processes.