Unveiling Key Limitations of ZnO/Cu₂O All-Oxide Solar Cells through Numerical Simulations

Abstract

ZnO/Cu2O solar cells emerge as one of the most promising technologies with significant potential when considering the Schockley–Queisser limit (SQL) and taking into consideration other important factors such as materials abundance, low-cost fabrication, suitable band alignment, and the possibility of having semitransparent devices. However, the actual efficiency values obtained are still far from the expected theoretical values. The reasons behind this are mainly attributed to the low control over the properties of the oxides and the lack of knowledge on how the final device performance is affected by both materials properties and cell architecture. To close this gap, we explore the working mechanism of ZnO/Cu2O junctions thanks to numerical simulations based on the SCAPS-1D software. In particular, the present study aims at investigating the limiting factors and key parameters that affect the behavior of the ZnO/Cu2O junctions. The impacts of altering the absorber and collector film thickness, the diffusion length, side illumination, and the concentration of defects at the junction interface are explored. The data indicate that the thickness of Cu2O is critical for the output results when correlated with the diffusion length, which in turn is strongly affected by the oxide deposition technique and conditions. Bifacial illumination demonstrates a significant enhancement of the power conversion efficiency, while defects at the interface inhibit the charge generation drastically and enhance recombination at the subcell level. This study provides an overarching view of cell behavior and different routes toward the improvement of ZnO/Cu2O devices.

A Review on Cu2O-Based Composites in Photocatalysis: Synthesis, Modification, and Applications

“…Compared with other semiconductors, copper(I) oxide (Cu 2 O) has the advantages of nontoxicity, a favorable environmental acceptability, low cost, and high activity. It has been widely used in solar cells [ 18 ], carbon monoxide oxidation [ 19 ], photocatalysts [ 20 ], electrocatalysts [ 21 ], and sensors [ 22 ]. As a p-type semiconductor, Cu 2 O has a bandgap width of 2.17 eV, and a broad response range to the solar spectrum.…”

Formation and Characterization of Stable TiO2/CuxO-Based Solar Cells

“…Among many heterojunction solar cells being considered in literature (see e.g., [ 57 , 58 , 59 , 60 , 61 , 62 , 63 ]), our group deals with TiO 2 /Cu x O and we already published several papers with investigations of TiO 2 and Cu x O cells fabricated with the direct current magnetron sputtering (DC-MS) with different process conditions [ 38 , 40 , 64 , 65 , 66 ]. In [ 64 ] TiO 2 , Cu 2 O, as well as TiO 2 /Cu 2 O, structures were investigated, with the wide variety of measurements carried out: morphology, cross-section, topography, roughness, and transmission spectra of the films.…”

Field-Effect Passivation of the Cu2O/ZnO Transparent Heterojunction Photovoltaic Device Using Ga2O3 Thin Film

“…These studies resulted in the importance of the passivation of heterojunction interfaces to enhance PV performance. Interfacial recombination is the expected loss mechanism in Cu 2 O solar cells ascribed to the high density of defect trap states and nonideal band alignment that limits the PV performance and is a primary region of low voltage. ,− The interfacial recombination can be minimized through passivation by either chemical or field induction. − The most viable approach to passivate the interface is field-effect passivation (FEP). In FEP, a suitable dielectric or n-type buffer layer between heterojunctions is used to enhance the junction quality. , Hence, Ga 2 O 3 was proposed as a suitable FEP buffer layer for Cu 2 O-based solar cells, providing the appropriate band alignment for V OC enhancement. , …”

“…Several numerical simulations and experimental studies were conducted to understand the origin of low photovoltaic (PV) performances ( V OC and J SC ) in Cu 2 O/ZnO-based solar cells. ,− One of the main attainments of these studies is the enhancement of PV performance by introducing the functional interfacial layer at the junctions that improve the interface quality. These studies resulted in the importance of the passivation of heterojunction interfaces to enhance PV performance.…”