Electrical сharacteristics study of heterojunction solar сells CdS/CIGS

In this work, we carried out the study of electrical characteristics with two-dimensional numerical analysis by using the Aided Design (TCAD Silvaco) software for CdS/CuInGaSe2 (CIGS) thin solar cells. Their structure is composed of a thin CIGS solar cell in the configuration: ZnO(200 nm)/CdS(50 nm)/CIGS (350 nm)/Mo. Then ZnO is used for conductive oxide contacted transparent front of the cell. For rear contact, the molybdenum (Mo) is used. The layer of the CdS window and the shape of the CIGS absorber is the n-p semiconductor heterojunction. The performance of the cell was evaluated by applying the defects created in the grain joints of polycrystalline CdS and CIGS material and CIGS/CdS interface in the model, and the physical parameters used in the TCAD simulations have been calibrated to reproduce experimental data. The J–V characteristics are simulated under AM1.5 illumination conditions. The conversion efficiency (η) 20.10% has been reached, and the other characteristic parameters have been simulated: the open-circuit voltage (Voc) is 0.68 V, the circuit-current density (Jsc) is equal to 36.91 mA/cm2, and the form factor (FF) is 0.80. The simulation results showed that the molar fraction x of the CIGS layer has an optimal value around 0.31 corresponding to a gap energy of 1.16 eV, this result is in very good agreement with that found experimentally.

Chemical Bath Deposition of Cd1−xZnxS as Buffer Layer in CIGS Solar Cell

Cd1-xZnxS thin films were deposited on glass substrates by chemical bath deposition (CBD). The effect of ZnSO4 solution concentration on the properties of the thin films was analyzed. The concentration of ZnSO4 solution affects the deposition rate of Cd1-xZnxS thin films. When the deposition rate is low, Cd1-xZnxS cubic crystal phase is formed. The surface morphology of hexagonal Cd1-xZnxS thin films is denser than that of cubic phase, the lattice mismatch rate of cubic phase Cd1-xZnxS thin films and CIGS is lower, only 0.56%, the interfacial state density is lower. SCAPS software was used to simulate the performance of the buffer layer, and the conversion efficiency of the cubic phase Cd1-xZnxS buffer layer in CIGS Solar Cell was up to 23.50%. Based on the EDS results, the function relationship between the contents of Zn2+ and Cd2+ in the films and the band gap content was deduced.

Numerical Investigation of Cu2O as Hole Transport Layer for High-Efficiency CIGS Solar Cell

Copper indium gallium selenide (CIGS) is an inexpensive material that has the potential to dominate the next-generation photovoltaic (PV) industry. Here we detail computational investigation of CIGS solar cell with encouragement of adopting cuprous dioxide (Cu2O) as a Hole Transport Layer (HTL) for efficient fabricated CIGS solar cells. Although Cu2O as a HTL has been studied earlier for perovskite and other organic/inorganic solar cell yet no study has been detailed on potential application of Cu2O for CIGS solar cells. With the proposed architecture, recombination losses are fairly reduced at the back contact and contribute to enhanced photo-current generation. With the introduction of Cu2O, the overall cell efficiency is increased to 26.63%. The wide-band of Cu2O pulls holes from the CIGS absorber which allows smoother extraction of holes with experiencing lesser resistance. Further, it was also inferred that, HTL also improves the quantum efficiency (QE) for photons with large wavelengths thus increases the cell operating spectrum.

A Numerical Investigation on the Combined Effects of MoSe2 Interface Layer and Graded Bandgap Absorber in CIGS Thin Film Solar Cells

The influence of Molybdenum diselenide (MoSe2) as an interfacial layer between Cu(In,Ga)Se2 (CIGS) absorber layer and Molybdenum (Mo) back contact in a conventional CIGS thin-film solar cell was investigated numerically using SCAPS-1D (a Solar Cell Capacitance Simulator). Using graded bandgap profile of the absorber layer that consist of both back grading (BG) and front grading (FG), which is defined as double grading (DG), attribution to the variation in Ga content was studied. The key focus of this study is to explore the combinatorial effects of MoSe2 contact layer and Ga grading of the absorber to suppress carrier losses due to back contact recombination and resistance that usually occur in case of standard Mo thin films. Thickness, bandgap energy, electron affinity and carrier concentration of the MoSe2 layer were all varied to determine the best configuration for incorporating into the CIGS solar cell structure. A bandgap grading profile that offers optimum functionality in the proposed configuration with additional MoSe2 layer has also been investigated. From the overall results, CIGS solar cells with thin MoSe2 layer and high acceptor doping concentration have been found to outperform the devices without MoSe2 layer, with an increase in efficiency from 20.19% to 23.30%. The introduction of bandgap grading in the front and back interfaces of the absorber layer further improves both open-circuit voltage (VOC) and short-circuit current density (JSC), most likely due to the additional quasi-electric field beneficial for carrier collection and reduced back surface and bulk recombination. A maximum power conversion efficiency (PCE) of 28.06%, fill factor (FF) of 81.89%, JSC of 39.45 mA/cm2, and VOC of 0.868 V were achieved by optimizing the properties of MoSe2 layer and bandgap grading configuration of the absorber layer. This study provides an insight into the different possibilities for designing higher efficiency CIGS solar cell structure through the manipulation of naturally formed MoSe2 layer and absorber bandgap engineering that can be experimentally replicated.

Impact of doping concentration, thickness, and band-gap on individual layer efficiency of CIGS solar cell

An investigation with the individual layer physical property of the CIGS solar cells is a significant parameter to design and fabricate highly efficient devices. Therefore, this work demonstrates the thickness and carrier concentrations doping dependence simulations using SCAPS 1D software. The optimized CIGS solar cells different layer properties such as short-circuit current density ([Formula: see text], open-circuit voltage ([Formula: see text], Fill Factor (FF) and conversion efficiency ([Formula: see text] with varying thickness and doped concentration are presented. This optimized layer by layer simulation work would be useful to build a suitable CIGS solar cell structure. This simulation investigation showed that an optimal CIGS device structure can be fabricated possessing the configuration of a window layer ZnO : Al thickness 0.02 [Formula: see text]m, ZnO layer thickness 0.01 [Formula: see text] m with [Formula: see text] = 10[Formula: see text] cm[Formula: see text] and [Formula: see text] = 10[Formula: see text] cm[Formula: see text], a CdS buffer layer thickness 0.01 [Formula: see text]m with [Formula: see text] = 10[Formula: see text] cm[Formula: see text] and absorber layer CIGS in the thickness range of 1–4 [Formula: see text]m with the doping level range [Formula: see text] = 10[Formula: see text]–10[Formula: see text] cm[Formula: see text], along with the optimal CIGS energy bandgap range of 1.3–1.45 eV. According to optimized simulation results, a CIGS solar cell device can possess electric efficiency 26.61%, FF 82.96%, current density of 38.21 mA/cm2 with the open circuit voltage 0.7977 eV. Hence, these optimized simulation findings could be helpful to provide a path to design and fabricate highly efficient CIGS solar cells devices.

Effect of the Properties of Chalcopyrite Semiconductors on the Physical and Optical Parameters of Cell Layers with CIGS

In this paper, the impact of various buffers of applying components on the effectiveness of CuInGaSe2 solar cells is studied numerically. The SCAPS software is employed to achieve the investigation. The main parameters of the inspected devices are: the photovoltaic conversion effectiveness (η), the filling factor (FF), short-circuit current (Jsc), and open circuit voltage (Voc). These photovoltaic parameters are analyzed vs. the thickness in the various buffer layers under study. The numerical findings revealed that the most significant conversion effectiveness (23.4%) of the CIGS solar cell is obtained with the CdS buffer layer. An attempt is conducted to improve this efficiency by using the SCAPS and by optimizing the two electrical and technological parameters of the three layers (ZnO, CdS, CIGS).