Maximum Absorption in Quantum Dot Solar Cell with Hyperbolic Band Model
Abhigyan Ganguly, Nandini Saha, Saradindu Panda, Bansibadan Maji, Madhuchhanda Choudhury
Department of Electronics and Communication, NIT, Silchar, India
Department of Electronics and Communication, St. Mary’s Technical Campus, India
Department of Electronics and Communication, Narula Institute of Technology, India
Department of Electronics and Communication, NIT, Durgapur, India
In recent times a steady decrease in fossil fuel calls for urgent replacement of conventional energy sources. Thus solar cells that utilizes sun light as its source of energy often considered as one of the best options available. But solar cells have certain limitations. A photon of energy (=Eg eV) can excite only one electron from valance band to conduction band but if photon has energy (hv) greater than the band gap value (Eg) of the material, then excess energy will generate heat instead of generating extra electron-hole pairs (EHPs). Thus the overall efficiency is limited and it is known as Schockly and Queisser limit, which gives the maximum efficiency at 31%. Hence recently semiconductor quantum dots have been incorporated in them to overcome this low efficiency problem. In this paper, we give an introduction to Quantum Dot Solar Cells (QDSCs) and its working principles at the beginning. The quantum effects found in QDSCs like quantum confinement and MEG is also explained. The relation between absorption coefficient (α) and wavelength (λ) is established and α v/s λ curve is plotted for different materials (GaAs, InP, InSb, CdSe and ZnS). The wavelength at maximum absorption peak is used to determine the corresponding QD band gap. Finally, using the QD band gap value corresponding to maximum absorption, the QD sizes for the considered materials are determined using Hyperbolic Band Model.
Solar cell; quantum dot; quantum dot solar cell; quantum confinement; electron-hole pairs (EHPs); hyperbolic band model