Influence of active layer thickness on electrical properties of P3HT/n-Si based hybrid heterostructure

Abstract

In the present study, we analyze the effect of active (organic) layer thickness on the optical and electrical properties of poly 3-hexylthiophene/n-silicon hybrid hetero-structure. The organic/inorganic sandwiched heterojunction have been prepared via spin-coating of poly 3-hexylthiophene film onto an oxide passivated Si substrate at room temperature. The device structure has been fabricated via depositing silver and aluminum contacts on Poly 3-hexylthiophene and n-silicon layers, respectively. The optical and electrical properties of the fabricated heterostructures have been examined by varying the active layer thickness from 50 to 120 nm. Photoluminescence measurements displayed a sharp intense peak at 578 nm corresponding to characteristic poly 3-hexylthiophene band-to-band transition. Enhancement in forward current and reduction in leakage current was observed with increased active layer thickness. It has been observed that employing an active layer thickness of 100 nm, the device produces enhanced forward currents with low leakage currents which leads to the formation of high quality heterojunction and demonstrates better performance of the device.