High Photoconductive Responsivity in Solution-Processed Polycrystalline Organic Composite Films

• Published in: Advanced functional materials Vol. 21; no. 5; pp. 927 - 931
• Main Authors: Hernandez-Sosa, Gerardo, Coates, Nelson. E, Valouch, Sebastian, Moses, Daniel
• Format: Journal Article
• Language: English
• Published: New York WILEY-VCH Verlag 08.03.2011; WILEY‐VCH Verlag
• Subjects: charge transport; Crystal structure; Crystallites; Gain; Occupation; organic electronics; Organic semiconductors; Photoconductivity; Photoluminescence; rubrene; Stemming
• ISSN: 1616-301X; 1616-3028; 1616-3028
• DOI: 10.1002/adfm.201002518

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. High photoconductive responsivity approaching 25 AW−1 in a solution‐processed organic composite of rubrene and 9,10‐diphenylanthracene. Studies of photoconductivity, photoluminescence, and structural order ellucidate the role of interfacial traps that lead to a long hole lifetime, which facilitates a high photoconductive gain, resulting in a high photoconductive responsivity.