Semi‐transparent NiO/ZnO UV photovoltaic cells

Abstract

Semi‐transparent pn‐heterojunctions were fabricated from pulsed laser deposited (PLD) n‐type ZnO and DC magnetron sputtered p‐type NiO, working as UV‐active solar cells. The complete cell stack has an average transmission of 46% in the visible spectral range and an optical absorption edge at 380 nm. The diodes exhibit high current rectification of up to eight orders of magnitude at ±2 V. Upon illumination with a solar simulator, the devices show photovoltaic activity with open‐circuit voltages of up to 520 mV, short‐circuit current densities of 0.5 mAcm2, and a maximum external quantum efficiency of 55%. However, we observed rather low fill factors of the current–voltage characteristics of around 40%, resulting in total power conversion efficiencies of around 0.1% and efficiencies in the UV range of 3.1%. To identify possible loss mechanisms, the voltage‐dependent efficiency of carrier collection was calculated. The data were fitted using a model that considers recombination losses at the NiO/ZnO interface as well as within the electric field region, yielding a high hole interface recombination velocity of 1×105cm s−1. We conclude that the carrier collection efficiency is strongly deteriorated by recombination losses at the NiO/ZnO interface, causing a strong bending of the jV characteristics under illumination and thereby low fill factors.

Self-rectifying resistive switching device based on n-ZnO/p-NiO junction

“…The hysteretic current-voltage (I-V) characteristics with self-rectifying effect are both found in the two cases. It confirms that the self-rectifying effect should be ascribed to the interface of n-ZnO/p-NiO, which is in agreement with the presence of p-n junction at the interface between n-ZnO and p-NiO in previous reports [19][20][21][22][23][24]. In the Au/ZnO/NiO/ ITO junction, it is difficult to distinguish high resistance state (HRS) and low resistance state (LRS) at positive bias.…”

“…For example, the conductive filaments of ZnO and NiO are considered to be related to oxygen vacancies or metal ions [15][16][17][18]. Actually, n-ZnO/ p-NiO junction has attracted much attention for the applications in the fields of light-emitted diode, ultraviolet detector, photocatalyst, photovoltaic cell, and piezoelectric nanogenerator over the past 20 years [19][20][21][22][23][24]. Both ZnO and NiO have been individually studied in resistive switching devices.…”

Suppression of Grain Boundary Scattering in Multifunctional p‐Type Transparent γ‐CuI Thin Films due to Interface Tunneling Currents

“…Since the idea of invisible circuits was conceived, transparent semiconductor devices have gained remarkable interest over the last years. For example, transparent solar cells, p‐n junctions, thin film transistors, photodetectors, or light‐emitting diodes have been reported. Another dimension of functionality can be added when taking into account transparent thermoelectric devices for power generation working at room temperature.…”

A self-powered solar-blind ultraviolet photodetector based on a Ag/ZnMgO/ZnO structure with fast response speed

“…However, p-type doping is still a big challenge for ZnO-based semiconductors, which hinders the further development of pn homojunction photodetectors. 20, 22,29 Although self-powered UV photodetectors can be demonstrated by combining n-type ZnO-based materials with other p-type layers, such as Si, 30,31 Cu 2 O, 32 NiO, 23,33 SiC, 34,35 GaN, 36,37 and organic materials, 38,39 they are usually limited by the unexpected visible/IR response from p-type materials, the lattice-mismatched heteroepitaxy, or the instability of organic materials. Therefore, ZnMgO Schottky junction photodetector should be a suitable choice to realize self-powered solar-blind UV detection.…”