Fabricating High-Quality Cu₂O Photocathode by Magnetron Sputtering: Insight into Defect States and Charge Carrier Collection in Cu₂O

Abstract

Earth-abundant Cu 2 O comprises one of the bestperforming photocathodes for solar-driven water splitting that provides a sustainable solution for the energy crisis. However, typical Cu 2 O photocathodes based on widespread electrochemical deposition (ED-Cu 2 O) hit a bottleneck in pursuing higher efficiency due to ED-Cu 2 O's inadequate electrical properties and excessive detrimental defects, demonstrating the need to explore alternative methods to fabricate a high-quality Cu 2 O film for further development of Cu 2 O photoelectric conversion. Here, commercial magnetron sputtering (MS) is exploited to manufacture a Cu 2 O photocathode (MS-Cu 2 O) with an appreciable electrical property and diminished point defects. Comprehensive optoelectronic properties characterization and energy band simulations unveil that the synchronous enhancement in electronic properties and charge carrier lifetime of MS-Cu 2 O benefiting from its suppressed defects relative to ED-Cu 2 O synergistically boosts its carrier collection efficiency and PEC performance. This work demonstrates the potential of MS in fabricating an energetic Cu 2 O photocathode to push the advancement of Cu 2 O photoelectrochemical catalysis.

High-performance p-type transparent conducting CuI–Cu2O thin films with enhanced hole mobility, surface, and stability

“…The resulting electron-neutralizing effect leads to a decrease in hole concentration within the films. 58,61 The hole concentration of Cu 2 O is lower than that of CuI, 62,63 and the elevated content of Cu 2 O in the films contributes to an overall reduction in hole concentration. As the O 2 flow rate rises, an increase in the density of grain boundaries ensues, amplifying the filtration of low-energy holes by these boundaries, thereby further decreasing hole concentration.…”

Key Strategies on Cu2O Photocathodes toward Practical Photoelectrochemical Water Splitting

“…magnetron-sputtered Cu2O photocathodes [65]. They demonstrated that the magnetron sputtering is more feasible to fabricate Cu2O photocathodes with less grain boundaries than electrodeposition (Figure 7b).…”

“…It facilitates the growth of highly-oriented Cu 2 O photocathode with less grain boundaries during the electrodeposition process (Figure 7a). Qin et al recently compared the characteristics of electrodeposited Cu 2 O photocathodes and magnetron-sputtered Cu 2 O photocathodes[65]. They demonstrated that the magnetron sputtering is more feasible to fabricate Cu 2 O photocathodes with less grain boundaries than electrodeposition (Figure7b).…”

Ab Initio Time-Domain Study of Charge Relaxation and Recombination in N-Doped Cu2O

“…As a p-type semiconductor with an intrinsic direct band gap of 2.17 eV, cuprous oxide (Cu 2 O) possesses a set of unique optical and electronic properties. , In addition, due to its low cost, nontoxicity, and high absorption rate in the visible region, it is regarded as one of the most promising materials for photovoltaic and photocatalytic application. − According to the Shockley–Queisser limit, Cu 2 O has been theoretically predicted to have a maximum power conversion efficiency of approximately 20% for solar cells, , while the achieved highest efficiency is only about 6.1% by now . Therefore, more research is needed to further optimize the material properties and then to improve the cell efficiency. , One way which is often used is to modulate the conductivity of the Cu 2 O films by doping, and nitrogen has been proved as an effective dopant. , Several experimental and theoretical studies have been dedicated to study the doping effects of nitrogen on the crystal structure, electronic structure, and optical properties of Cu 2 O. − Researchers found that nitrogen can be easily incorporated into the crystal lattice of Cu 2 O at high concentrations to substitute oxygen atoms and act as a p-type dopant, and some reported that an intermediate band forms in the gap by N doping.…”

“… 1 , 2 In addition, due to its low cost, nontoxicity, and high absorption rate in the visible region, it is regarded as one of the most promising materials for photovoltaic and photocatalytic application. 3 − 6 According to the Shockley–Queisser limit, 7 Cu 2 O has been theoretically predicted to have a maximum power conversion efficiency of approximately 20% for solar cells, 8 , 9 while the achieved highest efficiency is only about 6.1% by now. 10 Therefore, more research is needed to further optimize the material properties and then to improve the cell efficiency.…”