Influence of Te layer on CdTe thin films and their performance on CdS/CdTe solar cells

CdTe semiconductor is an absorbent material used in “tandem” photovoltaic solar cells. This material is commonly deposited by thermal evaporation presenting electrical resistivity values about of 105 W·cm to 109 W·cm. CdTe is applied in thin solar cells as p-type layer which is in contact with metal back electrode in solar cells. In the CdTe/metal junction a Schottky barrier exits; and small number of charge carriers have enough energy to get over the barrier and cross to the metal back contact. To solve part of this problem, nanostructured Te thin films were used as intermediate layers between CdTe and metal contact. Te layers whit different physical properties were deposited on CdS/CdTe structure by thermal evaporation employing different growth parameters. The electrical parameters of CdTe solar cells were influenced by p+ Te regions. p+ Te regions used as intermediate layer with large deposition time increases the FF and VOC values from 30% to 60% and 560 mV to 730 mV respectively. Also, the electrical resistivity is reduced from 106 W·cm to 103 W·cm. In this sense, Te region implemented as nanostructure allows to reduce the series resistance from 99 W to 20 W and increases the shunt resistance from 1445 W to 4424 W; Te region as thin films demonstrated not be adequate.

Perovskite Solar Cell design using Tin Halide and Cuprous Thiocyanate for Enhanced Efficiency

Utilization of Tin Halide as an absorber in Perovskite solar cells is immensely recognized as a substitute of lead halide absorber because of lead material’s toxicity. Also, Tin halide based Perovskites possess a potential for higher quantum efficiency because of their enhanced light absorption capability due to the wide-ranging absorption spectrum in the visible region with a comparatively lower bandgap of 1.3 eV than lead-based Perovskites. In the present work, glass/ transparent conductive oxide (TCO)/ titanium dioxide (buffer)/ tin halide Perovskite (Absorber)/ cuprous thiocyanate (HTM)/ Metal back solar cell structure has been designed and simulated by SCAPS software which yields Power Conversion Efficiency (PCE) of 28.32% and Fill Factor (FF) of 85.17%. The effect of total defect density, thickness, Valance Band Effective Density of States (VBEDS) and Conduction Band Effective Density of States (CBEDS) for an absorber layer has been analyzed. It has been observed that VBEDS variation has achieved PCE and FF to a significant extent i.e. up to 32.47% PCE and 85.86% FF