Invention of the CuInTe2 and CuInTe2-xSex Quantum Dots for Solar Cell Application

Abstract

CuInTe2 is one of the Ⅰ-Ⅲ-Ⅴ2 semiconductor which has chalcopyrite structure. And they have direct band gap (1.02eV) and large absorption coefficient, so they are potential candidate for photovoltaic device material.36 For example, bulk Cu(InGa)Se2 which has same chalcopyrite structure applied for solar cell and exhibited power conversion efficiency 19.5%. Also, many research group study Cu(InGa)Se2, CuInS2 and CuInSe2 quantum dots for LED, Solar cell. But one of the Te-containg material CuInTe2 has few¬ reported yet, even they can be using n-, p- type materials.34 For the first time, CuInTe2, CuInTe2-xSex gradient quantum dots were synthesized using hot-injection method. This research is not only about synthesizing this quantum dots but giving a promising nanomaterials for using solar cell. We found that CuInTe2, CuInTe2-xSex crystallites exhibited a chalcopyrite structure like bulky CuInTe2, CuInSe2 from XRD patteren. This also showed the XRD peak shift with ratio of each element. We used a XPS to analyze the bind energy of composit quantum dots and ICP-OES to determine the ratio of each element. The size of quantum dots with different growth time were characterized by TEM. In order to use solar cell, we determined by cyclovoltammetry(CV) the band gap and band gap position of Cu0.19In0.32Te0.23Se0.26. We designed the solution processed solar cell device using quantum dots and found that exhibited 17.4 mA/cm2 of short circuit current density (Jsc), 0.40 V of open circuit voltage (Voc), 44.1% of fill factor (F.F) and 3.1 % of overall power conversion efficiency at 100 mW/cm2 AM 1.5G illumination.