Design Optimization of Cesium Contents for Mixed Cation MA1-xCsxPbI3-Based Efficient Perovskite Solar Cell

Abstract

Perovskite solar cells (PSCs) have already been reported as a promising alternative to traditional energy sources due to their excellent power conversion efficiency, affordability, and versatility, which is particularly relevant considering the growing worldwide demand for energy and increasing scarcity of natural resources. However, operational concerns under environmental stresses hinder its economic feasibility. Through the addition of cesium (Cs), this study investigates how to optimize perovskite solar cells (PSCs) based on methylammonium lead-iodide (MAPbI₃) by creating mixed-cation compositions of MA_1-xCs_xPbI₃ (x = 0, 0.25, 0.5, 0.75, 1) for devices A to E, respectively. The impact of cesium content on the following factors, such as open-circuit voltage (V_oc), short-circuit current density (J_sc), fill factor (FF), and power conversion efficiency (PCE), was investigated using simulation software, with ITO/TiO₂/MA_1-xCs_xPbI₃/Spiro-OMeTAD/Au as a device architecture. Due to diminished defect density, the device with x = 0.5 (MA_0.5Cs_0.5PbI₃) attains a maximum power conversion efficiency of 18.53%, with a V_oc of 0.9238 V, J_sc of 24.22 mA/cm², and a fill factor of 82.81%. The optimal doping density of TiO₂ is approximately 10²⁰ cm^-3, while the optimal thicknesses of the electron transport layer (TiO₂, 10-30 nm), the hole-transport layer (Spiro-OMeTAD, about 10-20 nm), and the perovskite absorber (750 nm) were identified to maximize efficiency. The inclusion of a small amount of Cs may improve photovoltaic responses; however, at elevated concentrations (x > 0.5), power conversion efficiency (PCE) diminished due to the presence of trap states. The results show that mixed-cation perovskite solar cells can be a great commercially viable option because they strike a good balance between efficiency and performance.

Keywords: MA1−xCsxPbI3; Spiro-OMeTAD; TiO2; caesium; mixed-cation; perovskite solar cell; power conversion efficiency; simulation; solar cell.

Figure 1

(a) Shows the design architecture, while (b) demonstrates energy band diagrams of the suggested perovskite solar cell devices, such as (i) Device A (TiO₂/MAPbI₃/spiro-OMeTAD). (ii) Device B (TiO₂/MA_0.75Cs_0.25PbI₃/spiro-OMeTAD). (iii) Device C (MA_0.5Cs_0.5PbI₃/spiro-OMeTAD), (iv) Device D (TiO₂/MA_0.25Cs_0.75PbI₃/spiro-OMeTAD), and (v) Device B (TiO₂/CsPbI₃/spiro-OMeTAD), respectively.

Figure 2

Displays the photovoltaic parameters such as (a) open-circuit voltage, (b) short-circuit current, (c) fill factor, and (d) power conversion efficiency of MA_1−xCs_xPbI₃-based devices as Device A, Device B, Device C, Device D, and Device E, respectively, by the increasing function of the electron transport layer thickness.

Figure 3

Demonstrates the photovoltaic parameters such as (a) open-circuit voltage, (b) short-circuit current, (c) fill factor, and (d) power conversion efficiency of MA_1−xCs_xPbI₃-based devices as Device A, Device B, Device C, Device D, and Device E, respectively, by the increasing function of the doping density of TiO₂.

Figure 4

Illustrate the photovoltaic parameters, i.e., (a) open-circuit voltage, (b) short-circuit current, (c) fill factor, and (d) power conversion efficiency of MA_1−xCs_xPbI₃-based devices as Device A, Device B, Device C, Device D, and Device E, respectively, by the increasing function of spiro-OMeTAD thickness.

Figure 5

Illustrate the photovoltaic parameters, i.e., (a) open-circuit voltage, (b) short-circuit current, (c) fill factor, and as well as (d) power conversion efficiency of MA_1−xCs_xPbI₃-based all devices such as Device A, Device B, Device C, Device D, and Device E, respectively, by the increasing function of spiro-OMeTAD doping density.

Figure 6

Displays the photovoltaic parameters, i.e., (a) open-circuit voltage, (b) short-circuit current, (c) fill factor, and as well as (d) power conversion efficiency of MA_1−xCs_xPbI₃-based devices such as Device A, Device B, Device C, Device D, Device E, respectively, by the increasing function of the thickness of MA_0.25Cs_0.75PbI₃ (perovskite absorber layer).

Figure 7

Photovoltaics performance parameters of a solar cell as a function of cesium content (x, %): (a) short-circuit current (mA/cm²) and open-circuit voltage (V); (b) power conversion efficiency (PCE, %) and fill factor (%) as a function of Cs content for Device C, respectively.

Figure 8

(a) Open-circuit voltage as a function of temperature for devices A, B, C, D, and E, respectively. (b) Activation of energy derived from the y-intercept of (a) as a function of Cs concentration (x).

Figure 9

The photo current-voltage response of the most efficient Device C (ITO/TiO₂/MA_0.5Cs_0.5PbI₃/spiro-OMeTAD). The inset table of the figure shows the performance metrics derived from the J-V curve are as follows: open-circuit voltage of 0.92 V, short-circuit current density of 24.22 mA/cm², fill factor of 82.81%, and power conversion efficiency of 18.53%, respectively.