Fabrication and Photovoltaic of p-i-n Homojunction on Zinc Oxide

Transparent p-i-n junction based on ZnO was fabricated by radio-frequency magnetron sputtering and pulsed laser deposition methods, and its photovoltaic effect was examined. The p-type and i-type layers consist of CZO film (ZnO : CuO, optical energy gap Egopt= 3.0 eV) and undoped ZnO film (Egopt= 3.3 eV) fabricated using sputtering method, respectively. The n layer is GZO film (ZnO : Ga2O3, Egopt =3.6 eV) prepared by laser ablation method. For CZO films, an average transmittance of 63% in the visible region, the lowest resistivity of 26 Ω-cm and the maximum Seebeck coefficient of +200 μV/K were obtained. The photovoltaic effect was observed in a see-through structure of CZO/undoped ZnO/GZO/glass substrate by illumination of AM-1 light from both faces of the structure. It was recognized that in the series-connected-structure of CZO/ZnO/GZO + Si solar cell, the photovoltage was effectively caused with two peaks in the wavelength near 350 nm and 700 nm.