Thin films of CdTe semiconductor materials were grown on fluorine doped tin oxide (FTO) conducting glass substrates using the technique of electrodeposition. CdSO 4 at high concentrations and CdCl 2 , TeO 2 at low concentrations were used as precursor salts for electrodeposition. The range of deposition potentials was estimated using cyclic voltammetric measurements. The electrical, optical, structural and morphological characteristics of asdeposited and annealed CdTe thin films were characterized using photo-electrochemical (PEC) cell studies, UV-Vis spectrophotometry, X-ray diffraction (XRD) and scanning electron microscopy (SEM). These particular samples were converted from n-type into p-type after heat treatment. UV-Vis spectrometric measurements for CdTe layers indicated that, the energy band gaps of 1.45±0.02 eV for both asdeposited and annealed samples which exhibited the required optical property for fabricating CdS/CdTe solar cells. Little increase in (220) and (311) peaks of XRD spectra were observed for annealed layers compared to the as-deposited material. However, annealing exhibited a small reduction of cubic phase preferential orientation (111). The optical transmission for both as-deposited and annealed CdTe samples were about 60% for wavelengths longer than about 850 nm.
Dye-sensitized solid-state solar cells (DSSCs) replacing the liquid electrolyte with a p-type semiconductor have been extensively examined to solve the practical problems associated with wet-type solar cells. Here, we report the fabrication of a solid-state solar cell using copper iodide (CuI) as the hole conductor and alkyl-functionalized carbazole dye (MK-2) as the sensitizer. A DSSC sensitized with MK-2 showed a solar-to-electrical power conversion efficiency of 3.33% with a Voc of 496 mV and a Jsc of 16.14 mA cm-2 under AM 1.5 simulated sunlight. The long alkyl chains act as a barrier for charge recombination, and the strong accepting and donating abilities of the cyanoacrylic and carbazole groups, respectively, enhance the absorption of light at a longer wavelength, increasing the short-circuit current density. The efficiency recorded in this work is higher than similar DSSCs based on other hole collectors.
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