Abstract We present here for the first time the fabracition of a p-Cu 2 O/ZnO/AZO flexible heterojunction solar cell by electrodeposition of Cu 2 O thin film on a plastic substrate and sputtering of ZnO:Al layer. The Atomic Layer Deposition (ALD) has been employed to insert 5 nm ZnO as buffer layer. The heterojunction solar cell was characterized by Raman spectroscopy and scanning electron microscopy that show pyramidal shape and phonon modes for Cu 2 O thin film. Current–voltage ( J – V ), capacitance–voltage ( C – V ) and the external quantum efficiency (EQE) measurements were performed to understand the heterojunction properties. The solar cell device exhibits a power conversion efficiency of 0.897 ± 0.005% with an open circuit voltage of V oc = 300 mV, a short circuit current density of J sc = 6.819 ± 0.048 mA cm −2 and a fill factor of FF = 0.439 ± 0.006. The values of the built-in potential and the acceptor concentration at the junction were estimated from the reverse bias C – V measurement to be 0.37 V and 6.67 × 10 16 cm −3 , respectively.