Using covellite to control [hk1] orientation of antimony chalcogenide photoabsorbers

• Main Author: Panda, Deepan
• Other Authors: Lydia Helena Wong
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2023
• Subjects: Engineering::Materials::Microelectronics and semiconductor materials::Thin films
• Online Access: https://hdl.handle.net/10356/166648
• Institution: Nanyang Technological University

Antimony chalcogenides are a prime candidate for harvesting solar power due to their tuneable bandgaps, high absorption coefficient of 105 cm-1, and abundance of constituent elements. While antimony chalcogenides are promising as photoabsorbers, their anisotropic electrical conductivity requires preferred orientation to have efficient charge transport. While n-type materials were previously studied to induce this preferred orientation, this project investigates the use of covellite (CuS), a p-type material as a nucleating layer. Two fabrication methods for covellite were investigated. While chemical bath deposition yielded poorly crystalline covellite that was not able to induce [hk1]-orientation in antimony chalcogenide, spray pyrolysis produced more crystalline covellite with a dendritic microstructure, which provided [hk1]-oriented photoabsorber when 30% Se was added to the hydrothermal reaction mixture during a 4 h reaction. When device fabrication was completed by deposition of cadmium sulphide electron transport layer and platinum catalyst layer, the resulting device showed an appreciable photocurrent of 0.95 mAcm-2, with an onset potential of 0.61 V relative to reversible hydrogen electrode.