Substrate temperature dependent performance of near infrared photoresponsive organic field effect transistors based on lead phthalocyanine

Abstract In order to study the dependence of device performance on substrate temperature ( T sub ), lead phthalocyanine (PbPc) photoresponsive organic field-effect transistors were fabricated at different substrate temperatures and characterized. We observed as T sub rises, the photoresponsivity ( R ) and the maximum photo/dark current ratio ( P max ) of the devices first increase and then decrease, and an optimal device performance is provided at T sub = 140 °C, at which the R and P max of the device reach maximum simultaneously. This is mainly a result of competition between the enhanced NIR absorption originating from the increasing proportion of triclinic phase in PbPc films with rising T sub and the decreased carrier mobility at higher substrate temperatures, as evidenced by optical absorption spectrum, X-ray diffraction and atomic force microscopy investigations.