Study of photoexcitations in poly(3-hexylthiophene) for photovoltaic applications

Abstract

We used a variety of steady state and transient optical techniques for studying the primary and steady state photoexcitations in pristine films of poly(3-hexylthiophene) [P3HT] with different molecular weight used for organic photovoltaic solar cells. The employed techniques include picosecond transient and steady state photoluminescence and photomodulation spectroscopies, laser action, and doping induced absorption. We show that solar cell device qualities based on donor-acceptor blends of the P3HT polymers with substituted fullerene molecules crucially depend on the polymer properties, which can be readily discerned by the steady state photomodulation technique. This technique can, therefore, be applied to specific polymer donors for estimating their solar cell device properties prior to actually fabricating an optimal device.