Cu2ZnSnSe4 Solar Cells with Absorbers Prepared by the Metallic Ink-Printing Method Using Nanosized Cu-Zn-Sn Pastes and Selenization

A large-grained Cu2ZnSnSe4 (CZTSe) absorber for solar cells was fabricated by the metallic ink-printing method and subsequent selenization at 600A degrees C to 700A degrees C with overpressures of two different selenium compounds and a step-heating procedure. The developed CZTSe grain size was confirmed as 8 mu m to 20 mu m. The second heating stage was helpful in inducing crystallization and was important for grain growth. For the nonvacuum approach, nanosized Cu, Zn, and Sn powders were chosen for preparing inks. Ceramic Al2O3 was used instead of glass to prevent the thermal decomposition of the substrate. A nanosized Cu(In,Ga)Se-2 layer was coated on a Mo electrode to provide a barrier to avoid direct contact of Cu, Zn, and Sn with Mo. The selenization under the combination of two selenide pellets played a crucial role in preparing the CZTSe absorber. The fabricated CZTSe solar cell device showed power conversion efficiency of 1.14%, open-circuit voltage of 130 mV, short-circuit current density of 33.1 mA/cm(2), and fill factor of 0.265.