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We report the properties of hybrid deposited iron pyrite (FeS2) thin films applied as the back contact interface layers of CdS/CdTe solar cells. The hybrid deposition process for FeS2 optimized in this study relies on DC magnetron sputtering of iron with simultaneous thermal evaporation of sulfur. We have fabricated solar cells incorporating CdS/CdTe window/absorber layers sputter-deposited onto commercial transparent conducting oxide coated glass and have compared the performance of devices incorporating the new FeS2/Cu/Au back contacts with that of standard devices incorporating Cu/Au back contacts. Considering our best devices of each type, the inclusion of the FeS2 thin film as a hole transport layer has improved the open circuit voltage VOC by 2.1%, reaching 817 mV, and the fill-factor FF by 8.3% relative, reaching 74.7%, in comparison with devices omitting the FeS2 layer. Under standard test conditions of 100 mA/cm2 simulated AM1.5G and 25 °C, devices utilizing the FeS2 hole transport layer have shown a conversion efficiency η as high as 13.3% – a relative increase in η of ~10% over our current laboratory standard back contact. The attained FF exceeds previous results for high efficiency sputter-deposited CdS/CdTe solar cells.

Local density of state (LDOS), current–voltage characteristic ( I – V characteristic) and differential conductance (DC) of pure and defected zigzag and armchair graphene nanoribbons quantum dots (GNRQDs) are investigated. We found that for the pure systems of armchair GNRQDs, the DC has oscillation feature where these oscillations could be explained by 1D characteristic of atomic wires. In our samples, these wires constructed from sites with the same symmetry along the GNRQD length. Some of these wires have metallic features while some of them show semiconducting features. The zigzag GNRQDs have approximately ohmic behavior. Also it is found that the defected DC significantly depend on vacancy position.