Yttrium-doped zinc oxide as a terawatt-scale transparent conducting oxide

The desirable features of an ideal transparent conducting oxide for terawatt-scale solar cells include abundant raw materials, low cost, high performance, and low process temperature. In this paper we examine all the Group IIIA and IIIB elements as potential n-type dopants for ZnO and suggest yttrium as an ideal dopant for this purpose. Experimental results on electrodeposited yttrium-doped ZnO are presented. The lowest resistivity in yttrium-doped ZnO is 6.3×10 ^-5 Ω-cm, while the average resistivity is ∼2×10 ^-4 Ω-cm. The maximum process temperature is 300°C. The transmittance of yttrium-doped ZnO is ∼80%. Thermal stability of yttrium-doped ZnO is also investigated. It has a real chance to become an industry standard transparent conducting oxide for terawatt-scale solar cells, as its performance is comparable to indium tin oxide, its deposition is solution-based, and yttrium is abundant.