Electrical performance of organic/inorganic hybrid solar cell devices based on n-type GaAs substrate orientations and a conjugated polymer (PANI)

This article presents the electrical performance of hybrid organic/inorganic solar cell devices. Hybrid polyaniline (PANI)/n-GaAs photovoltaic devices were fabricated by spin coating of PANI thin films on conventional (100) and high index (311)A and (311)B n-GaAs substrates. The solar cell parameters of these devices, as obtained by current density–voltage (J–V) under illumination conditions, were found to be dependent on the substrate orientation. The PANI/(311)A n-GaAs devices revealed the best performance, with an open-circuit voltage (Voc) of 207 mV, a short-circuit current density (Jsc) of 0.267 mA/cm2, a fill factor (FF) of 25% and an efficiency ( $$\eta$$ ) of 1.4 x 10-2% which is higher than that of PANI/(100) and (311)B hybrid samples. Additionally, the electrical properties of these junction diodes have been studied utilizing dark current density–voltage (J–V), capacitance–voltage (C–V), deep level transient spectroscopy (DLTS) and Laplace DLTS techniques. The dark J–V measurements showed that the rectification ratio (IF/IR), turn-on voltage (Von) and barrier height ( $$\phi _b$$ ) of PANI/(311)A n-GaAs heterostructure are higher than those of PANI thin films deposited on (100) and (311)B n-GaAs substrates. The DLTS and Laplace DLTS measurements illustrated that the number of traps in PANI/(311)A n-GaAs devices is lower than that in PANI/(100) n-GaAs and PANI/(311)B n-GaAs devices, corroborating with J–V results.