Photovoltaic conversion enhancement of a transparent NiO/CdO/ZnO pn junction device with a CdO transition layer

Abstract A transparent NiO/CdO/ZnO pn junction film device with a CdO transition layer is prepared via a simple continuous sol-gel and sputtering method. Here, the ZnO is prepared via a simple sol-gel method, the CdO transition layer is also deposited via the sol-gel method on the surface of the ZnO film, and subsequently, the dense NiO film is deposited via the sputtering method on the surface of the CdO transition layer. As revealed, the as-prepared transparent device exhibits a high transmittance of ~75%, obvious photovoltaic conversion enhancement (photocurrent) of ~104 (9600)-fold compared with the unmodified device, and better stability during 6000 cycles, which can be mainly ascribed to the CdO transition layer. Thus, the appropriate Fermi level can provide an ideal channel for charge carrier transport, and the visible light response can increase the number of photogenerated charge carriers.