Polycrystalline Cu2O photovoltaic devices incorporating Zn(O,S) window layers

Abstract

The tunability of the Zn(O,S) conduction band edge makes it an ideal, earth-abundant heterojunction partner for Cu 2 O, whose low electron affinity has limited photovoltaic performance with most other heterojunction candidates. However, to date Cu 2 O/Zn(O,S) solar cells have exhibited photocurrents well below the entitled short-circuit current in the detailed balance limit. In this work, we examine the sources of photocurrent loss in Cu 2 O/Zn(O,S) solar cells fabricated by sputter deposition of Zn(O,S) on polycrystalline Cu 2 O substrates grown by thermal oxidation of Cu foils. X-ray photoelectron spectra reveal that Zn(O,S) deposited at room temperature leads to a thin layer of ZnSO 4 at the Zn(O,S)/Cu 2 O interface that impedes current collection and limits the short circuit current density to 2 mA/cm 2. Deposition of Zn(O,S) at elevated temperatures decreases the presence of interfacial ZnSO 4 and therefore the barrier to photocurrent collection. Optimal photovoltaic performance is achieved at a Zn(O,S) deposition temperature of 100 °C, which enables an increase in the short circuit current density to 5 mA/cm 2 , although a small ZnSO 4 layer is still present. Deposition at temperatures above 100 °C leads to a reduction in photovoltaic performance. Spectral response measurements indicate the presence of a barrier to photocurrent and exhibit a strong dependence on voltage and light bias, likely due to the photodoping of Zn(O,S) layer.

Metal Oxide Thin-Film Heterojunctions for Photovoltaic Applications

“…Previous studies of the ZnO/Cu 2 O heterojunction have indicated that a conduction band offset of 0.2–0.3 eV yields the highest open circuit voltage [8,9]. To lower the conduction band offset for the ZnO/Cu 2 O heterojunction solar cell there are several materials that can potentially be used as buffer layers, including Ga 2 O 3 (χ = 4.0 eV), TiO 2 (χ = 4.0 eV), ZnS (χ = 3.9 eV), GaN (χ = 3.5 eV), Ta 2 O 5 (3.2 eV), and various ZnO alloys [11,18,19]. Many of these materials have been implemented as buffer layer in experimentally realized ZnO/Cu 2 O heterojunction solar cells, but a relatively low performance has usually been achieved [7,20].…”

Tailor‐Designed Porous Catalysts: Nickel‐Doped Cu/Cu2O Foams for Efficient Glycerol Electro‐Oxidation

“…The electrochemical behavior of the electrodeposited Cu/ Cu 2 O foams onto the above well-cleaned copper rod surface was studied in 0.1 M KOH (Figure 1). All the electrodeposited Cu/Cu 2 O foams exhibited multiple redox peak couples corresponding to the transition between various copper oxidation states (e. g., Cu 2 O, CuO, Cu(OH) 2 and CuOOH). [40] During the positive-going potential scan, metallic Cu is first oxidized into Cu 2 O (~À 0.50 V, peak (a)).…”

“…Copper-based catalysts have attracted significant interest over the years, [1][2][3] especially in the field of electrocatalysis, thanks to their high electro-catalytic activities, low cost, abundance and good electrical conductivities. [4][5][6] For instance, copper-based nanomaterials have been considered as promising electrocatalysts for potential applications including reduction of CO 2 , [7] water splitting, [8] fuel cells [9,10] and oxidation of several organic compounds such as methanol, [11] glycerol, [12] aliphatic diols and carbohydrates.…”

Complex Investigation of High Efficiency and Reliable Heterojunction Solar Cell Based on an Improved Cu2O Absorber Layer

“…The electrical properties of the absorber (Cu 2 O) and buffer layer (ZnO) from the structure of the top subcell were analyzed using Silvaco Atlas software. The implementation of defects, as well as the study of two efficient materials (ZnO and Ga 2 O 3 ) for the buffer layer were investigated [13][14][15][16][17] and several analyses were considered using the Takiguchi model [7]. A transition interface defect layer (IDL) was introduced as well.…”