Graded Bandgap Ultrathin CIGS Solar Cells

Abstract

In this paper, we physically modeled passivated ultrathin Cu (In1−xGax) Se2 solar cells with different bandgap grading configurations. Firstly, we have designed the cell architecture according to the fabricated model. The novelty in this work is the modeling of passivated u-CIGS solar cells with different bandgap grading profile configurations in order to achieve high efficiency with a thickness of 500 nm. A significant influence on device performance has been observed while changing absorber doping density, electron affinity, and operating temperature (range of 10–70 °C) for the investigated samples. ZnS has been used as a buffer layer to replace the conventional CdS material in order to improve cell efficiency. The impact of the buffer doping density and electron affinity on u-CIGS cell performance is explored. The simulation results show that a high bandgap at the front and rear sides with an acceptor density of 2 × 1016 provide the best electrical cell parameters: Jsc of 31.53 mA/cm2, Voc of 742.78 mV, FF of 77.50%, η of 18.15%. Our findings can be considered guidelines for new single and/or tandem cell optimization to achieve high efficiency.

Upper Subcell Impacts on Perovskite/u-CIGS Tandem Solar Cell Performance

“…The tandem device has been performed using TCAD tools. The physical parameters of the structure were carefully selected to make the models as realistic as possible, and they have been tabulated in detail in our previous work [14,31]. following cell as a good top subcell which consists of SnO 2 , Perovskite, and Spiro-OMeTAD as an electron extraction layer (ETL), an absorber layer, and a hole extraction layer (HTL), respectively [30].…”

“…In contrast, a single u-CIGS bottom sub-cell with a low bandgap absorber (1.15 eV) is utilized to absorb the filtered low-energy photons, full-area front buffer layer, and Molybdenum rear contact with fixed widths grid and full-area on passivation layer using Al 2 O 3 to reduce the rear recombination [31][32][33][34][35]. Figure 3 illustrates J-V and EQE characteristics of the calibrated u-CIGS, perovskite, and perovskite/u-CIGS tandem models.…”

“…Figure 3 illustrates J-V and EQE characteristics of the calibrated u-CIGS, perovskite, and perovskite/u-CIGS tandem models. The physical properties of each layer were taken from reported research articles in order to match the fabricated models [30][31][32][33][34][35]. Table 1 represents the electrical characteristic of the cell models concerned [30,32].…”

Efficiency improvement of Cu(In(1−x)Ga x )Se2 solar cell using copper barium tin sulfide as back surface field layer and bandgap grading technique

“…CIGS is an attractive material for the absorber layer in the PV cell because it has a direct bandgap and its energy bandgap tunes with the variation in composition x, which is shown in equation ( 1) [7,11,22] x = Ga (In + Ga)…”

“…The solar frontier achieved 23.35% efficiency of CIGS solar cells by sulfurization after selenization methods [10]. A theoretical investigation of bandgap grading of CIGS solar cell obtained an efficiency of 18.15% [11]. Sobayel et al used a CIGS photovoltaic device with cubic silicon carbide as a buffer and obtained a PCE of 25.51% [6].…”