Efficiency improvement of Cu2O-based heterojunction solar cells fabricated using thermally oxidized copper sheets

• Published in: Thin solid films Vol. 559; pp. 105 - 111
• Main Authors: Minami, Tadatsugu, Miyata, Toshihiro, Nishi, Yuki
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 30.05.2014; Elsevier
• Subjects: Applied sciences; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Diffusion; interface formation; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Energy; Exact sciences and technology; Ga2O3; Heterojunction; High-efficiency; Laser deposition; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Natural energy; p-Cu2O; Photovoltaic conversion; Physics; Solar cell; Solar cells. Photoelectrochemical cells; Solar energy; Solid surfaces and solid-solid interfaces; Surface double layers, schottky barriers, and work functions; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Solar cell; Ga2O3; High-efficiency; p-Cu2O; Heterojunction; Semiconductor thin films; Oxide layer; Doping; Polycrystal; Pulsed laser deposition; p n heterojunctions; AND circuit; Thin film; Photovoltaic cell; O; Work function; Semiconductor heterojunctions; n type semiconductor; Laser ablation technique; Ga; Copper; Diffusion; p-Cu; Surface conditions; Interface; Damaging
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2013.11.026

This paper introduces the present status and prospects for further efficiency improvement of Cu2O-based p–n heterojunction solar cells that feature an n-type oxide semiconductor thin film/p-Cu2O sheet structure. This structure was achieved by both stabilizing the surface of polycrystalline p-Cu2O sheets that had been prepared by thermal oxidization of Cu sheets and also developing low-temperature and low-damage deposition technology for applying thin films as an n-oxide semiconductor layer. The highest efficiency of 5.38% and open circuit voltage of 0.8V were obtained in an AZO/n-Ga2O3/p-Cu2O heterojunction solar cell fabricated with a non-doped Ga2O3 thin film prepared on a Cu2O sheet at room temperature with a thickness of 75nm under an O2 gas pressure of 1.7Pa by a pulsed laser deposition. It should be noted that the obtainable photovoltaic properties in AZO/n-oxide semiconductor/p-Cu2O heterojunction solar cells are considerably more affected by the surface condition of the p-Cu2O layer, i.e., the interface at the heterojunction, than the diffusion potential resulting from the difference of work functions between the p-Cu2O and n-semiconductor layers. To achieve a higher efficiency in AZO/n-oxide semiconductor/p-Cu2O heterojunction solar cells, it is necessary to improve the interface at the heterojunction as well as reduce the series resistance and increase the parallel resistance of the heterojunction solar cells. •Present status and prospects for further development of Cu2O-based heterojunction solar cells.•Mg1-XZnXO multicomponent oxide thin films were used as an n-oxide semiconductor layer.•Photovoltaic properties were considerably improved by stabilizing the surface of Cu2O sheets.•Thin films were prepared using low-temperature and low-damage deposition technology.•RTA treatments or Pd-Sn catalyst coating were performed to achieving higher efficiency.