Exploring illumination effect on the impedance spectroscopy and dielectric dispersion of 5,10,15,20-tetrakis(4-methoxyphenyl)-2 1H, 23H-porphine cobalt(Ⅱ)/silicon heterojunction photovoltaic

摘要

The dynamic properties of a hybrid heterojunction based on a small molecule of 5, 10, 15, 20-tetrakis (4-methoxyphenyl)-21H, 23H-porphine cobalt(Ⅱ), CoTMPP, grown onto p-Si wafer have been studied using impedance spectroscopy (IS) at various frequency range (102-106 Hz) under different illumination intensities (0-24 mW/cm~2) at room temperature. The fabricated Al/p-Si/CoTMPP/Au heterojunction performs two relaxation processes associated with Al/p-Si and p-Si/CoTMPP interfaces are attributed to a Maxwell-Wagner-Sillars (MWS) effect causes charge accumulation at interfacial regions. With increasing illumination intensity, the MWS effect enhances and leads to more accumulated charges at the interfacial regions. Based on Nyquist plots fitting, the equivalent circuit of the fabricated device was modeled. The dielectric dispersion, electric modulus, relaxation process and electrical conductivity were investigated under different illuminations. The present results revealed an excellent photoresponse and photo-resistive of the Al/p-Si/CoTMPP/Au device as a candidate for photovoltaic devices and optoelectronics applications.