Photocarrier generation and bipolar transport in diphenoquinone doped polymethylphenylsilane thin films

Abstract

Bipolar transport and photocarrier generation processes in thin films of 3,5-dimethyl-3′,5′-di- tert-butyl-4,4′-diphenoquinone (MBDQ) doped polymethylphenylsilane (PMPS) are studied in terms of optical absorption, photoluminescence, the standard time-of-flight, and electroabsorption experiments. With increasing MBDQ concentration, the electron drift mobility is observable above 30 wt. % MBDQ addition (5.0×10−7 cm2/Vs at 40 wt. % MBDQ addition) and the hole drift mobility is unchanged (∼1.0×10−4 cm2/Vs) for 0–40 wt. % MBDQ addition. The photocarrier generation efficiency is increased by an order of magnitude over pristine PMPS for 30–40 wt. % MBDQ addition in a visible spectral range. The electroabsorption experiments of MBDQ/PMPS composites show that the existence of charge transfer states becomes evident with increasing MBDQ concentration, which facilitate the photocarrier generation in the spectral range.