Exploration and optimization of different charge transport layers for Cs4CuSb2Cl12 based perovskite solar cells

Abstract

Recently, lead-free Cs₄CuSb₂Cl₁₂ has garnered attention as an excellent material to be used as an absorber of perovskite solar cells (PSCs). In this work, Cs₄CuSb₂Cl₁₂ absorber-based PSCs were studied and the conditions to get high performance for PSCs were investigated. Here, six different materials for electron transport layers (ETLs) and 10 different materials for hole transport layers (HTLs) were studied. A numerical approach was followed by using SCAPS-1D simulator. During the work, various device parameters of PSC were investigated such as thickness variation of the absorber and ETL layers, acceptor density variation of the absorber and HTL layers, variation of the donor density of the ETL layer, and effect of total defect density of absorber. Also, other parameters such as the impact of resistance, temperature, J-V graph, Q-E graph, and carrier generation rate at different positions of the PSCs were assessed. Among the studied 10 HTL materials, MWCNTs outperformed other studied materials, hence it was selected for further investigations. Then the structures were optimized based on the device parameters outcome, and the structure having MZO and STO ETLs both showed the maximum power conversion efficiency (PCE) of 28.23%. (Al/FTO/MZO/Cs₄CuSb₂Cl₁₂/MWCNTs/Au) the structure showed an open-circuit voltage (V_oc) of 1.249 V, short-circuit current density (J_sc) of 25.11 mA/cm² and a fill factor (FF) of 90.1%. The performance was also evaluated with respect to key electrical parameters. Optimum performance was achieved at a series resistance of 1 Ω·cm² and a shunt resistance of 1000 Ω·cm², beyond which performance gains saturated. The other best-performing STO ETL-based (Al/FTO/STO/Cs₄CuSb₂Cl₁₂/MWCNTs/Au) structure had V_oc of 1.25 V, J_sc of 25.11 mA/cm², and FF of 90.01% Under the optimized condition other structure with CdS, PC₆₁BM, SnS₂ and ZnSe ETLs showed PCE of 27.68%, 27.8%, 25.67% and 28.22%. This work gives good insights into several Cs₄CuSb₂Cl₁₂ based PSC structures and shows in the future they have great potential to be developed practically for highly efficient performances.

Keywords: Cs4CuSb2Cl12 absorber; MWCNT HTL; Perovskite solar cell; SCAPS-1D; ZnSe ETL.

Fig. 1

Cs₄CuSb₂Cl₁₂ based proposed PSC device structures.

Fig. 2

Energy band alignment of the studied PSC device structures based on various ETL materials with MWCNTs as the HTL.

Fig. 3

Comparison of performances of HTL materials on PSC parameters.

Fig. 4

Effect of (a) thickness variation of absorber, and (b) thickness variation of ETL on device performance (PCE, FF, V_OC, and J_SC) .

Fig. 5

Significance of variation of absorber (a) acceptor density, and (b) defect density on device performances.

Fig. 6

Effect of (a) donor density of ETL, (b) acceptor density variation of HTL on device performances.

Fig. 7

Effect of variation of (a) series resistance, (b) shunt resistance, and (c) temperature on V_OC (V), J_SC (mA cm^− 2), FF (%) and η (%).

Fig. 8

Contour mapping of PCE photovoltaic parameter with respect to thickness of absorber, and total density of absorber in device structures based on various ETL materials.

Fig. 9

Contour mapping of PCE photovoltaic parameter with respect to acceptor density and total defect density variation on various ETL materials based PSC devices.

Fig. 10

Carrier generation rate (a) before optimization (b) after optimization in the device structures. Carrier recombination rate (c) before optimization, (d) after optimization in the device structures.

Fig. 11

(a) J-V curve before optimization, (b) J-V curve after optimization, (c) quantum efficiency before optimization, and (d) quantum efficiency after optimization in the device structures.