Research Article Investigation of the Performance of a Sb 2 S 3 -Based Solar Cell with a Hybrid Electron Transport Layer (h-ETL): A Simulation Approach Using SCAPS-1D Software Pierre Gérard Darel Kond Ngue , 1 Ariel Teyou Ngoupo , 1 Aimé Magloire Ntouga Abena, 1 François Xavier Abomo Abega , 2 and Jean-Marie Bienvenu Ndjaka 1 1 University of Yaoundé I, Faculty of Science, Department of Physics, P.O. Box: 812, Yaoundé, Cameroon 2 University of Ebolowa, Higher Institute of Agriculture, Forestry, Water and Environment (HIAFWE), P.O. Box: 118, Ebolowa, Cameroon Correspondence should be addressed to Ariel Teyou Ngoupo; arielteyou@yahoo.fr Received 13 September 2023; Revised 28 February 2024; Accepted 19 March 2024; Published 8 April 2024 Academic Editor: Qiliang Wang Copyright © 2024 Pierre Gérard Darel Kond Ngue et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. In order to reduce current leakage and improve electron transfer in solar cells, charge transport layers (CTL), mainly hybrid electron transport layers (h-ETL), are considered as a solution. In this research contribution, computational analysis using SCAPS-1D software is performed to explore the output photovoltaic parameters of a Sb 2 S 3 -based solar cell with h-ETL. No theoretical works on this configuration have been previously reported. The main objectives of the present work are to propose a h-ETL with good band alignment with the Sb 2 S 3 absorber, high transparency, and Cd free; to mitigate the instability and cost issues associated with using Spiro-OMeTAD HTL; and to optimize the solar cell. Thus, we calibrated the J -V characteristics and electrical parameters of the FTO/(ZnO/TiO 2 )/Sb 2 S 3 /Spiro-OMeTAD/Au solar cell by numerical simulation and compared them with those of the experiment. Subsequently, our simulations show that to replace the TiO 2 ETL used in the experiment and to form the h-ETL with ZnO, IGZO is found to be a good candidate. It has better band alignment with the Sb 2 S 3 absorber than TiO 2 ETL, which reduces the trap states at the ETL/Sb 2 S 3 interface; it has high transparency due to its wide bandgap; and an intense electric field is generated at the IGZO/Sb 2 S 3 interface, which reduces the recombination phenomenon at this interface. MoO 3 , MASnBr 3 , Cu 2 O, CuI, and CuSCN HTL were also tested to replace the Spiro-OMeTAD HTL. Simulation results show that the cell with MoO 3 HTL achieves higher performance due to its high hole mobility and high quantum efficiency in the visible region; it also allows the solar cell to have better thermal stability (TC = −0 32%/K) than the cell with Spiro-OMeTAD HTL (TC = −0 53%/K). The parameters that could improve the solar cell efficiency (η) obtained after these substitutions were also optimized. In particular, the parameters of the Sb 2 S 3 absorber layer (thickness, defect density, and doping), ETL and HTL layer thicknesses, h-ETL/Sb 2 S 3 interface defect density, and series and shunt resistances have been optimized. Finally, by combining high performance and thermal stability, the results show that the thermal stability of the solar cell depends on the back contact type; thus, nickel (Ni) was found to combine high performance and better thermal stability among the back contacts investigated. After these improvements, the efficiency of the Sb 2 S 3 -based solar cell increased from 5.08% (J SC = 16 19 mA/cm 2 , V OC =0 56 V, and FF = 55 40%) to 15.43% (J SC = 18 51 mA/cm 2 , V OC =1 11 V, and FF = 74 76%). This study proposes an approach to optimize the Sb 2 S 3 upper subcell for tandem solar cells. 1. Introduction Interest in solar cells based on antimony trisulfide (Sb 2 S 3 ) is growing due to the exceptional optoelectronic properties of this new emerging photovoltaic material. Sb 2 S 3 is a p- type semiconductor with a high absorption coefficient (α > 10 5 cm -1 ) in visible light [1] and an appropriate band- gap (1.7-1.8 eV) for the upper subcell in double-junction tandem solar cells [2]. Furthermore, Sb 2 S 3 is a binary compound without secondary phases, and due to its low melting point (~550 ° C), layers of high crystalline quality can be synthesized at low temperatures (<350 ° C) [2]. In Hindawi International Journal of Photoenergy Volume 2024, Article ID 5188636, 23 pages https://doi.org/10.1155/2024/5188636