Effect of a buffer layer on the photovoltaic properties of AZO/Cu_2O Solar Cells

摘要

The effect of a buffer layer and/or interface region on the photovoltaic properties of Al-doped ZnO (AZO)/Cu_2O heterojunction solar cells was investigated. The Ⅰ-Ⅴ characteristics and photovoltaic properties in AZO/ZnO-In_2O_3/Cu_2O devices were considerably improved by increasing the Zn content (Zn/(In+Zn atomic ratio)) of the ZnO-In_2O_3 thin-film buffer layer. In addition, the photovoltaic properties of AZO/Zn_(1-X) Mg_XO/Cu_2O devices were found to degrade significantly as the composition (X) was increased above approximately 0.1 because of the increase in resistivity of the buffer layer. Although the spectral response of photocurrent observed in AZO/Zn_(1-X)Mg_XO/Cu_2O devices was considerably affected by altering the value of X, the photo-generated hole in the buffer layer of these devices was not successfully injected into the Cu_2O. AZO/Cu_2O heterojunctions fabricated using Cu_2O sheets with a sulfurized surface exhibited ohmic Ⅰ-Ⅴ characteristics.