Temperature independent exciton relaxation in poly(di-n-hexylsilane) confined in nanoporous silica

Exciton relaxation kinetics of poly(di-n-hexylsilane) (PDHS) confined within 10-nm size pores of silica matrix SBA-15 was investigated by frequency domain fluorometry in the 10–300 K temperature range. Temperature independent exciton lifetimes of 0.66 ns and 0.28 ns were determined for the PDHS in the aggregated form (up to 300 K) and in trans form (up to 200 K), respectively, indicating the constant luminescence quantum yield and the temperature insensitive nonradiative relaxation upon confinement of PDHS into nanopores. The absence of thermal activation of nonradiative decay is most likely caused by severely restricted exciton migration towards quenching centers in low-dimensional structures.