Synthesis of visible-light-absorptive and hole-transporting periodic mesoporous organosilica thin films for organic solar cells

Periodic mesoporous organosilica (PMO) thin films that possess both visible-light absorption and hole-transporting properties were synthesized from a newly designed 4,7-dithienyl-2,1,3-benzothiadiazole (DTBT)-bridged organosilane precursor using polystyrene-block-poly(ethylene oxide) (PS-b-PEO) as a template. DTBT-based PMO films were successfully obtained from the 100% organosilane precursor without the addition of other alkoxysilanes such as tetraethyoxysilane and by control of the tetrahydrofuran-ethanol solvent ratio and the PS/PEO group ratio in the block copolymer. The PMO films possess connected cage-like mesopores with diameters of ca. 15-20 nm, which could be derived from templating with spherical micelles. The PMO films exhibited absorption in the visible range between 400 and 650 nm and hole-transport mobility in the order of 10(-5) cm(2) V-1 s(-1) We demonstrate that the PMO thin film functions as a p-type layer for organic solar cells by filling an n-type [6,61-phenyl C-61 butyric acid methyl ester into the mesopores.