Although pyrite (FeS2) is abundant, getting a single-phase pyrite thin film is difficult due to the coexistence of various phases of iron and sulfur in nature. We propose an ink-based process for attaining the pyrite phase of iron sulfide. This work involves degassing Iron (II) chloride in an octadecylamine solution and later reflux with addition of sulfur in diphenyl ether at 200°C. The process yielded phase-pure single crystalline pyrite nanocrystals which were later cleaned and dispersed in chloroform for uniform suspension. Thus obtained nanocrystals were deposited as thin films using drop casting and spin coating. Solar cells were fabricated using CdS as an n-type window layer in a superstrate configuration. When tested, the superstrate type FeS2 nanoparticle cell showed 0.03% with high Voc of 565 mV.

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We report CdTe/CdS solar cell with CdTe layer grown by sputtering method. A controlled etch and anneal process on the sputter-grown CdTe films was performed to increase the average grain size of the film. The process involved dipping the CdTe films in a saturated solution of cadmium chloride (CdCl 2 ) in methanol (2.08 gram in 100 ml) followed by a 30 minute annealing at 400 °C. We performed various experiments on this process by varying the dipping times, drying process and annealing times and analyzed the resultant films using Scanning Electron Microscopy (SEM). We could see a clear increase in grain size from 200 nm to 5 µm after CdCl 2 treatment. The process also increased the overall roughness of the sample so that more light is absorbed than reflected. We prepared solar cells using CdTe as p-type layer and CdS as n-type layer. The efficiency of the cell improved from 1.1% to 4.2% after air annealing. The effect of air-annealing is studied by means of quantum efficiency measurement.