Numerical design and optimization of copper tin sulphide (CTS) sensitizer based quantum dot solar cell

Abstract

This work presents, for the first time, the theoretical design of an efficient CTS quantum dot sensitized solar cell (QDSSC), ITO/TiO₂/CTS/HTL/Au, with an efficiency of 17.86 %, with CuSbS₂ as the hole transporting layer (HTL). Using SCAPS-1D software, optimization of each layer is done and a thorough investigation on defect densities, on layers as well as interfaces, is performed. Lower sensitizer thickness (1––10 nm) and higher HTL thickness (1 µm) are favourable for good efficiency. Defect densities of 10¹⁰ cm⁻² to 10¹⁸ cm⁻² are permissible for the sensitizer layer as well as for the TiO₂/CTS interface. Only the defects in the HTL and CTS/HTL interface were found to affect the cell efficiency and so these defects should be kept at a minimum of 10¹⁰ cm⁻². The sensitizer being quantum dots, the predominant recombination is non– radiative, Shockley Read Hall recombination; Auger recombination was found to be negligible. The cell efficiencies reported in the paper are above the efficiencies reported for the thin film solar cells of CTS. The novelty of this work is that a practical, environment friendly, cost effective and efficient quantum dot sensitized solar cell has been proposed, taking into account all of the resistive parameters which could affect the cell efficiency in real.