Development of Back and Front Contacts for CdTe Layer in Tandem Flexible Photoelectric Converters on Basis of CdTe/CuInSe2

M G Khrypunov,N A Kovtun,I V Khrypunova,D A Kudii,M M Kharchenko

doi:10.1155/2019/9535123

Abstract

By the method of nonreactive high-frequency magnetron sputtering on Upilex polyimide films, transparent and conductive layers of ITO were obtained. These layers, after high-temperature annealing, at temperatures typical for the solar cell formation, had a resistance of 11 ohm/□ and a transmittance of up to 72%. The use of such an ITO layer with the addition of a 100 nm thick layer of undoped zinc oxide, as the front contact, and Cu/ITO composition, as the back contact, made it possible to obtain a flexible solar cell polyimide/ITO/CdS/CdTe/Cu/ITO with an efficiency of 10.4%. With a thickness of the base layer of cadmium telluride 2.5 μm, the average transmittance of the SC in the 850-1100 nm wavelength range is 46.8%. The developed design of a flexible solar cell based on cadmium telluride due to the use of a transparent back contact with a comb metal electrode is easily interfaced with existing designs of flexible solar cells based on copper and indium diselenide, which allow the formation of flexible tandem photoelectric converters CdTe/CuInSe2.

Highlights

At present, economical technologies for the formation of base and interfacing layers of thin-film solar cells are being developed as an alternative to widely used solar cells (SCs) based on crystalline silicon [1,2,3,4,5,6]
In order to study the evolution of the crystal structure, the optical and electrical properties of the initial ITO layers during the formation of flexible solar cells based on CdS/CdTe, ITO films obtained at different deposition temperatures on polyimide substrates were annealed in air at 430°C for 25 minutes
After annealing in air at 430°C for 25 minutes, the surface resistivity of the ITO layers formed on the polyimide film increases to 11 ohm/□; the transmittance coefficient increases to 72%

Summary

Introduction

Economical technologies for the formation of base and interfacing layers of thin-film solar cells are being developed as an alternative to widely used solar cells (SCs) based on crystalline silicon [1,2,3,4,5,6]. The modern direction of increasing the efficiency of photoelectric conversion is the creation of tandem instrument structures. In the design of tandem photoelectric converters, it is promising to use film solar cells with a base layer of CdTe and CuInSe2. One of the stages in the development of efficient flexible solar cells based on CdS/CdTe is the development of a technology for obtaining transparent and electrically conductive front electrodes. For the use of CdS/CdTe film solar cells in tandem photoelectric converters, these solar cells should have transparent back electrodes. The development of back and front electrodes for wide-band base layers of flexible tandem photovoltaic converters based on CdTe/CIS is an actual problem; the solution of which will allow the creation of film flexible instrument structures with an efficiency higher than the efficiency of solar cells based on crystalline silicon

Technique for Obtaining Samples and Carrying Out Experimental Studies

Results and Discussion

Conclusions