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ARTICLE

Studying the effect of copper on the p-ZnTe/n-AgCuInSe₂/p-Si for thin films solar cell applications

R. H. Athab, B. H. Hussein^*

Department of physics, College of Education for Pure Science / Ibn Al-Haitham, University of Baghdad, Baghdad, Iraq

* Corresponding Author:

Chalcogenide Letters 2023, 20(2), 91-100. https://doi.org/10.15251/CL.2023.202.91

Received 21 September 2022; Accepted 01 February 2023;

Abstract

A thin film of AgInSe₂ and Ag_1-xCu_xInSe₂ as well as n-Ag_1-xCu_xInSe₂ /p-Si heterojunction with different Cu ratios (0, 0.1, 0.2) has been successfully fabricated by thermal evaporation method as absorbent layer with thickness about 700 nm and ZnTe as window layer with thickness about 100 nm. We made a multi-layer of p-ZnTe/n-AgCuInSe2/p-Si structures, In the present work, the conversion efficiency (η) increased when added the Cu and when used p-ZnTe as a window layer (WL) the bandgap energy of the direct transition decreases from 1.75 eV (Cu=0.0) to 1.48 eV (Cu=0.2 nm) and the bandgap energy for ZnTe=2.35 eV. The measurements of the electrical properties for prepared films showed that the D.C electrical conductivity (σd.c) increased with increasing Cu content for AgCuInSe2 thin films. So the electrical conductivity changed from 1 (Ω.cm) ^-1 to 29.96 (Ω.cm) ^-1 when x changed from 0.0 to 0.2. The prepared thin films have two activation energies (E_a1 & E_a2) in the temperature ranges of (300-393) K and (303-473) K. The C-V measurements revealed that all prepared heterojunctions were of the abrupt type and the junction capacitance reduced while the width of depletion region and the built-in potential increased with increasing the Cooper content. The current-voltage characteristics under dark condition of AgCuInSe2 heterojunctions, the current-voltage measurements under illumination showed that the performance of heterojunction solar cell improved with increasing Cu content. The result indicated that the prepared solar cell with 0.2 Ag content exhibited the highest efficiency (η = 1.68%) compared to other prepared solar cells.

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