Computational study of KGeCl3 perovskite solar cells toward high efficiency via electron transport innovation

Abstract

Germanium-based perovskite solar cells (PSCs) have gained attention as a promising alternative to conventional lead-based PSCs due to their environmentally friendly and non-toxic nature. However, their efficiency remains below optimal levels, requiring further exploration to enhance their performance. This study investigates a novel n-i-p structured germanium-based perovskite solar cell using the wxAMPS simulation. The baseline structure-FTO/TiO₂/KGeCl₃/Spiro-OMeTAD/Au-achieved a power conversion efficiency (PCE) of 18.55%. To improve efficiency, various electron transport layer (ETL) materials were evaluated, including TiO₂, IGZO, SnO₂, ZnO, ZnSe₂, WO₃, PCBM, and WS₂ TMDC. The results revealed that the WS₂ emerging as the most suitable candidate. Optimization of key parameters, including the thicknesses of WS₂ ETL (50 nm), Spiro-OMeTAD HTL (30 nm), and the absorber layer KGeCl₃ (600 nm), significantly improved device performance. Additional investigations into defect density, acceptor concentration, electron affinity, and donor concentration further optimized the device's operation. The study also analyzed the adverse effects of functional temperature, providing insights into stability and efficiency under real-world conditions. The optimized solar cell device demonstrated enhanced performance metrics: V_oc = 1.02 V, J_sc = 25.77 mA/cm², FF = 78.25%, and PCE = 22.98%. These findings highlight the potential of germanium-based perovskite solar cells as a sustainable, lead-free photovoltaic solution. The integration of WS₂ as an ETL paves the way for achieving high-efficiency, environmentally friendly solar cells, with promising implications for advancements in renewable energy solutions.

Keywords: Efficiency; Electron transport layers (ETLs); Perovskite solar cells (PSCs); wxAMPS simulation.

Fig. 1

The configuration of the simulated perovskite solar cell, along with the band diagram of the n-i-p perovskite solar cell at equilibrium.

Fig. 2

(a) The IV-Curve and (b) the QE (rescaled range) of the simulated cell architecture for different ETLs.

Fig. 3

The photovoltaic parameters of the simulated cell architecture (a) J_sc, (b) V_oc, (c) FF, and (d) PCE of the CFTS-based solar cells for TiO₂, IGZO, SnO₂, ZnO, ZnSe₂, WO₃, PCBM, and WS₂ TMDC ETLs.

Fig. 4

Corresponding band energy diagrams of planar perovskite solar cells using Spiro-OMeTAD as HTM and different ETMs.

Fig. 5

The obtained photovoltaic parameters versus the different ETL thicknesses with (a) J_sc, (b) V_oc, FF, and (d) PCE.

Fig. 6

The simulated photovoltaic results versus the ETL electron affinity with (a) J_sc, (b) V_oc, (c) FF, and (d) PCE.

Fig. 7

The photovoltaic parameters as a function of the donor concentrations of the ETL with (a) J_sc, (b) V_oc, (c) FF, and (d) PCE.

Fig. 8

(Color online) Contour mapping of the optoelectronic parameters for the KGeCl₃ absorber solar cell device thickness and WS₂ ETL thickness.

Fig. 9

(Color online) Contour mapping of the cell performance of thickness and defect density of the KGeCl₃ absorber layer.

Fig. 10

(Color online) Contour mapping of the solar cell performance of thickness and doping density of the absorber layer.

Fig. 11

The change of the Spiro-OMeTAD HTL thickness with (a) J_sc, (b) V_oc, (c) FF, and (d) PCE. The thickness changes from 30 to 80 nm.

Fig. 12

Influence of the operating temperature of the KGeCl₃ Perovskite solar cells (a) J_sc, (b) V_oc, (c) FF, and (d) PCE.