Speaker: Laila Parvin Poly, ECpE Graduate Student
Advisor: Vikram Dalal
Title: A Study of Cadmium Selenide Solar Cells
Abstract: CdSe is a II-VI group semiconductor chalcogenide which is potentially an attractive material for photovoltaic energy conversion since its bandgap is around the value (∼1.7 eV) needed for use in a tandem junction solar cell with silicon acting as the bottom cell. Theoretical calculations indicate that it is possible to attain a thermodynamic efficiency of ∼45% in a tandem cell of CdSe and c-Si. It is a direct bandgap semiconductor and, consequently, only a thin film is needed to absorb most of the photons. CdSe thin films can be deposited using different techniques including thermal evaporation, close-spaced sublimation and sputtering. In this work, we report on deposition of CdSe thin films using physical vapor deposition at a high growth temperature of ∼400 °C with different thicknesses in the range of 0.5 µm–3 µm. We show that postdeposition treatments using CdCl2 increases the grain size and the mobility of CdSe significantly. Heterojunction devices were made on FTO coated glass substrates using n-CdS as the n-heterojunction layer and organic materials such as PTAA, P3HT and PEDOT:PSS as the p-type heterojunction layer. Various film and device properties have been measured using capacitance- voltage, capacitance-frequency-temperature, quantum efficiency-voltage techniques etc.
Bio: Laila Parvin Poly is a Ph.D. candidate at Iowa State University. She received her B.S. degree in electrical engineering in 2015 from Bangladesh University of Engineering and Technology (BUET). She is currently pursuing her Ph.D. degree at Iowa State University in electrical engineering with a focus in Microelectronics and Semiconductor Device Physics. Her current research interests involve fabrication and characterization of thin film polycrystalline solar cells based on Cadmium Selenide.