Influence of P+-ZnTe back surface contact on photovoltaic performance of ZnTe based solar cells

Abstract

In order to improve photovoltaic performance of solar cells based on ZnTe thin films two device structures have been proposed and its photovoltaic parameters have been numerically simulated using Solar Cell Capacitance Simulator software. The first one is the ZnO/CdS/ZnTe conventional structure and the second one is the ZnO/CdS/ZnTe/P +-ZnTe structure with a P +-ZnTe layer inserted at the back surface of ZnTe active layer to produce a back surface field effect which could reduce back carrier recombination and thus increase the photovoltaic conversion efficiency of cells. The effect of ZnO, CdS and ZnTe layer thicknesses and the P +-ZnTe added layer and its thickness have been optimized for producing maximum working parameters such as: open-circuit voltage Voc, short-circuit current density Jsc, fill factor FF, photovoltaic conversion efficiency η. The solar cell with ZnTe/P +-ZnTe junction showed remarkably higher conversion efficiency over the conventional solar cell based on ZnTe layer and the conversion efficiency of the ZnO/CdS/ZnTe/P +-ZnTe solar cell was found to be dependent on ZnTe and P +-ZnTe layer thicknesses. The optimization of ZnTe, CdS and ZnTe layers and the inserting of P +-ZnTe back surface layer results in an enhancement of the energy conversion efficiency since its maximum has increased from 10% for ZnO, CdS and ZnTe layer thicknesses of 0.05, 0.08 and 2 µm, respectively to 13.37% when ZnO, CdS, ZnTe and P +-ZnTe layer thicknesses are closed to 0.03, 0.03, 0.5 and 0.1 µm, respectively. Furthermore, the highest calculated output parameters have been Jsc = 9.35 mA/cm 2 , Voc = 1.81 V, η=13.37% and FF= 79.05% achieved with ZnO, CdS, ZnTe, and P +-ZnTe layer thicknesses about 0.03, 0.03, 0.5 and 0.1 µm, respectively. Finally, the spectral response in the long-wavelength region for ZnO/CdS/ZnTe solar cells has decreased at the increase of back surface recombination velocity. However, it has exhibited a red shift and showed no dependence of back surface recombination velocity for ZnO/CdS/ZnTe/P+-ZnTe solar cells.

Performance Enhancement of an MoS2-Based Heterojunction Solar Cell with an In2Te3 Back Surface Field: A Numerical Simulation Approach

“…Furthermore, the placement of BSF between the absorber and rear electrode can minimize the absorber layer thickness, minimizing the PV cell's overall cost. 33,34 In this article, the photovoltaic performance parameters of the proposed (ITO/TiO 2 /MoS 2 /In 2 Te 3 ) MoS 2 -based thin-film heterojunction SC without and with BSF have been analyzed utilizing the SCAPS-1D simulator. The investigation of the influence of the thickness, carrier concentration, defect density, working temperature, band alignment, rear electrode, capacitance−voltage (C−V), and back surface recombination velocity (SRV) on SC output parameters has been performed for optimizing the device structure as well as to determine better photoconversion efficiency in a cost-effective way.…”

“…The BSF layer has been developed in this study with 50 nm-thick indium telluride (In 2 Te 3 ) in the molybdenum disulfide (MoS 2 ) solar cell, because of its ability to accumulate holes more effectively as well as reduces electron–hole recombination. Furthermore, the placement of BSF between the absorber and rear electrode can minimize the absorber layer thickness, minimizing the PV cell’s overall cost. , …”

Synthesis and electrophysical properties of CdS/ZnTe heterojunctions

“…The CVC measurements in a temperature range of 30-100 °C showed that the current exhibits an exponential dependence on applied voltage in a region of up to 1.6 V (Fig. 3); it can be approximated by the following expression: (1) where I o is the reverse current of the p-n heterojunction, q is the electron charge (q = 1.6  10 19 C), k is the Boltzmann constant (k = 1.38  10 23 J deg), and T is the temperature (K), n-ideality factor. A graphical representation of this dependence is shown in Fig.…”

“…The best known thin-film heterojunction solar cells are those made of CdS/CdTe. However, the possibility of designing other pairs of heterojunction systems based on А 2 В 6 compounds and solar cells based on these systems, in particular, CdS/ZnTe, is of interest [1,[3][4][5][6][7]. The theoretically calculated model of a CdS/ZnTe junction [2,3] for an optimum ZnTe thickness of 2 m gives an efficiency value of 10%, an open-circuit voltage (U OC ) of 1.81 V, and a short-circuit current density (J SC ) of up to 7 mA/cm 2 at a current-voltage characteristic (CVC) fill factor of 78.84%.…”

Tuning structural, electrical, linear, and nonlinear optical properties of cadmium zinc telluride quantum dot thin films

“…The use of dual semiconductor materials of zinc telluride and cadmium telluride thin films is crucial in various significant scientific and technological applications, such as solar cells and electronic devices [1][2][3][4][5][6][7], light-emitting diodes [8], and photodetectors [9]. This significance is due to their electronic and optical properties, where the dual systems of CdTe and ZnTe have a wide direct bandgap that allows their application as absorbing layers in solar cells [10][11][12][13], and they are also characterized by their high absorption coefficient that reaches 10 5 cm −1 [12][13][14][15].…”