Metal Oxide Thin-Film Heterojunctions for Photovoltaic Applications

• Published in: Materials Vol. 11; no. 12; p. 2593
• Main Authors: Nordseth, Ørnulf, Kumar, Raj, Bergum, Kristin, Fara, Laurentiu, Dumitru, Constantin, Craciunescu, Dan, Dragan, Florin, Chilibon, Irinela, Monakhov, Edouard, Foss, Sean Erik, Svensson, Bengt Gunnar
• Format: Journal Article
• Language: English; Norwegian
• Published: Switzerland MDPI AG 19.12.2018; MDPI
• Subjects: band alignment; Buffer layers; Conduction bands; Copper oxides; cuprous oxide; Defects; Efficiency; Energy; Hall effect; heterojunction; Heterojunctions; interface defects; Magnetic properties; magnetron sputtering; Majority carriers; Mathematical models; Metal oxides; modelling; Optical properties; Photovoltaic cells; Radio frequency; Silicon; Simulation; Solar cells; Spectroellipsometry; Substrates; thin film; Thin films; Zinc oxide; United States > US; Norway; Romania; heterojunction; magnetron sputtering; thin film; cuprous oxide; interface defects; band alignment; modelling
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma11122593

Silicon-based tandem solar cells incorporating low-cost, abundant, and non-toxic metal oxide materials can increase the conversion efficiency of silicon solar cells beyond their conventional limitations with obvious economic and environmental benefits. In this work, the electrical characteristics of a metal oxide thin-film heterojunction solar cell based on a cuprous oxide (Cu₂O) absorber layer were investigated. Highly Al-doped n-type ZnO (AZO) and undoped p-type Cu₂O thin films were prepared on quartz substrates by magnetron sputter deposition. The electrical and optical properties of these thin films were determined from Hall effect measurements and spectroscopic ellipsometry. After annealing the Cu₂O film at 900 °C, the majority carrier (hole) mobility and the resistivity were measured at 50 cm²/V·s and 200 Ω·cm, respectively. Numerical modeling was carried out to investigate the effect of band alignment and interface defects on the electrical characteristics of the AZO/Cu₂O heterojunction. The analysis suggests that the incorporation of a buffer layer can enhance the performance of the heterojunction solar cell as a result of reduced conduction band offset.