Preparation and characteristics of CuGaSe2/CdS solar cells

Abstract

p-CuGaSe2/n-CdS heterojunctions have been prepared by depositing CdS films on p-type CuGaSe2 single crystals whose initial resistivity was 10−2 Ω cm and changed to 1 Ω cm after the CdS film deposition. The CdS films, which were grown by a multisources method, exhibit a room-temperature resistivity of 0.1 Ω cm. The absolute quantum efficiency of these devices as photovoltaic detectors reaches the value of 80% at a wavelength of 5800 Å. As solar cells, these heterojunctions at 25 °C display a solar power conversion efficiency of 5% when they are exposed to the solar light whose intensity is 71 mW/cm2. When the heterojunctions are directly polarized, they emit light in a broad band which is centered at ∼7700 Å. An external electroluminescent emission efficiency of about 0.05% has been measured at liquid-nitrogen temperature.

Why CuInGaSe2 and CdTe polycrystalline thin film solar cells are more efficient than the corresponding single crystal?

“…In 1977, depositing by flash-evaporation a CdS thin film onto a single crystal of p-CuGaSe 2 , a solar cell that exhibited an energy conversion efficiency up to 7 % was realized [17]. CuInSe 2 is a semiconducting compound of the I-III-VI 2 family with a direct band gap of 1,05 eV.…”

Structural and optical properties of CuGaSe2 layers grown by the hot wall epitaxy method

“…7 shows a diagram of the n-CdS/p-CGS junction. As shown in the subfigure, it is fabricated to a p-n.junction between the p-CGS layer as the absorber material and the n-CdS layer [30]. The solar-cell parameters obtained from the J-V characteristic are given in Table 4.…”

Phase Transformation of Se/(Cu,In,Ga)/Mo/Glass Thin Films: A Real-Time Synchrotron X-ray Scattering Study

“…It has a chemical formula of CuIn x Ga 1−x Se 2 , where the value of x can vary from 1 (pure CIS) to 0 (pure CGS). [2][3][4] CIGS is a tetrahedrally bonded semiconductor, with the chalcopyrite crystal structure, 5 and a bandgap varying continuously with x from about 1.0 eV (for CIS) to about 1.7 eV (for CGS). 6 7 CIGS is best known as an alternate solar cell material in thin-film solar cells.…”