Optimization of Zn concentration in chemically deposited (Cd _x –Zn_1−x )S nanocrystalline films for solar cell applications

Abstract

An attempt has been made to optimize the Zn concentration in chemically deposited (Cd x -Zn 1−x )S (x =0.2, 0.4, 0.6, 0.8) films on ITO substrate by varying the Cd/Zn composition ratio to enable them to absorb a sizable fraction of solar photons. The phase purity and nanocrystalline character of as-deposited films are established by x-ray diffractometer. Lattice parameters and band-gap values are found to change almost linearly with Cd/Zn composition ratio. The surface morphology supports the nano-crystalline nature of deposited films. The E g values for (Cd x -Zn 1−x )S nanocrystalline films estimated from absorption spectra and corresponding Tauc's plots range from 2.63 to 2.81 eV. The optical behavior in terms of absorption and photoluminescence spectra suggests that these films are suitable for application in photovoltaic devices. The electrical resistivity of different (Cd x -Zn 1−x )S films has been measured as a function of Zn concentration. The efficiency of resultant CdTe/(Cd x -Zn 1−x )S cell is calculated to be approximately 11%.

Doping Behavior of Zn in CdS and Its Effect on the Power Conversion Efficiency of the Cu2ZnSn(S, Se)4 Solar Cell

“…Absorption measurement is performed to study the effect of Zn doping on the bandgap of Zn x Cd 1 – x S. Based on the Tauc relation and absorption coefficient (α) of the Zn x Cd 1 – x S extracted from the absorption spectra, the bandgap is estimated to be 2.38, 2.43, 2.47, and 2.51 eV, respectively, for the Zn x Cd 1 – x S with x = 0, 0.14, 0.26, and 0.32, as shown in Figure . The bandgap of Zn x Cd 1 – x S increases with increasing Zn doping concentration, in agreement with other experimental results qualitatively. ,, …”

“…The bandgap of Zn x Cd 1 − x S increases with increasing Zn doping concentration, in agreement with other experimental results qualitatively. 19,36,37 A batch of CZTSSe solar cells with ZCS#0, 1, 2, and 3 as the buffer layer was prepared to investigate the influence of Zn doped CdS on the photovoltaic performance of CZTSSe solar cells. J−V measurement was conducted for the batch of CZTSSe solar cells.…”

Formation of wide-bandgap, highly transparent and compact Cd1−xZnxS films with dynamically controlled pH in chemical bath deposition

“…Therefore, low pH is found to be suitable for the heterogeneous reaction and a viable route for the formation of high Zn containing Cd 1− x Zn x S films, free from the coverage area problem widely reported in the literature. 10,25,36…”

Opto-Electronics Review

“…It is well known that polycrystalline CdS thin films are widely popular as window material in several heterojunction solar cells, such as CdS/CdTe for their favorable optical properties [113,114]. Recently, there have been so many reports on the application of CdS as a window layer in CdS/CuInSe2, CdS/CdTe and CdS/Cu(InGa)Se2 [115][116][117][118] high-efficiency solar cells.…”