High Photoconductive Responsivity in Solution-Processed Polycrystalline Organic Composite Films

We demonstrate a novel approach for enhancing photoconductive responsivity (R) using a solution-based organic semiconductor composite that yields R approaching 25 AW(-1), which is two to three orders of magnitude higher than the R in films comprising a single molecular component. We present extensive studies of photoconductivity, photoluminescence, and crystalline structural order that elucidate the mechanisms underlying this high photoconductive responsivity. The high R is found to arise from high photoconductive gain (82) due to a long mobile hole lifetime stemming from a prolonged occupation of electrons in deep traps generated at interfacial regions between the molecular crystallites.