Influencing parameters on the electrochemical growth of V2O5 nanorods on ITO as interfacial layer in bulk heterojunction polymer solar cells

This work demonstrates the influencing parameters on the physicochemical and electrochemical characteristics of vanadium pentoxide (V2O5) nanostructures electrochemically grown on the ITO electrode as the hole transporting layer (HTL) in polymer solar cells (PSCs). V2O5 nanostructures were formed using the low cost precursor of ammonium metavanadate by cyclic voltammetry. Tuning the solution concentration and the initial nucleation time of the precursor resulted in the growth of V2O5 nanorods (NRDs). The structural, morphological, optical, and electrochemical properties of the synthesized V2O5 nanostructures were compared. The influences of V2O5 nanostructures morphologies on the charge transfer and charge recombination rate of the active layer-coated samples were investigated using electrochemical impedance spectroscopy and photoluminescence spectroscopy techniques. Results showed that V2O5 NRDs formed a three-dimensional microporous network with orthorhombic structure on the ITO, possessing an electroactive surface area of 0.23 cm2 and excellent conductivity of 0.04 mS cm−1. The highest charge mobility of 8.31 × 10−2 cm2.V−1s−1 was observed for the V2O5 NRDs which was about 169% and 17% higher than that obtained for other V2O5 morphologies. V2O5 NRDs-HTL based PSC showed a short circuit current of 9.21 mA cm2, an open-circuit voltage of 0.54 V, a fill factor of 63.50%, and a power conversion efficiency of 3.18%, which were higher than that considered for the reference PSC prepared base on PEDOT:PSS as the HTL.