Improvement of WSe/sub 2/ solar cells by doping?

In order to, improve the ohmic back contact of ZnO/WSe/sub 2/ solar cells, W, Ta, Mo, and Au have been investigated as contact materials. After annealing, RF-magnetron-sputtered Mo contacts exhibited the lowest contact resistance (0.006 Omega cm/sup 2/). ZnO/WSe/sub 2//Mo solar cells with a series resistance of about 2.7 Omega cm/sup 2/ and a fill factor of up to 67% were fabricated. Compared to earlier published fill factor values, this gives an improvement of more than 10%. The influence of the tungsten source material as well as the dopants Mo, Cu, Cr, and V on ZnO/WSe/sub 2/ solar cells was studied. The highest open-circuit voltage of 515 mV (85-mW/cm/sup 2/ illumination) was obtained with a Cu-doped diode. All Mo-doped solar cell had the highest short circuit current density (18.0 mA/cm/sup 2/). Mo and O/sub 2/-doped solar cells exhibit the best power conversion efficiencies, up to 6.7%. All diodes were characterized by temperature-dependent I-V, frequency and voltage-dependent impedance, spectral response and electron-beam-induced current (EBIC) measurements.<
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