Influence of a bifunctional linker on the loading of Cu2AgInS4 QDs onto porous TiO2 NFs to use as an efficient photoanode to boost the photoconversion efficiency of QDSCs

Abstract

In the present study, quaternary Cu₂AgInS₄ quantum dots (CAIS QDs) are synthesized by a hot injection method. The crystallographic information of the QDs is confirmed by X-ray diffraction and high-resolution transmission electron microscopy studies. Energy dispersive X-ray spectrum analysis reveals a 1.93 : 1.0 : 1.01 : 3.80 elemental composition ratio of the synthesized QDs. X-ray photoelectron spectroscopy analysis confirms the oxidation states of the elements present in the synthesized QDs. The optical properties are studied using UV-VIS absorption spectroscopy and PL emission spectroscopy. From a Tauc plot, the bandgap of the synthesized QDs is calculated to be 1.6 eV. The synthesized QDs are used as sensitizers and are loaded onto P-TiO₂ NFs using 3-mercaptopropionic acid as a bifunctional linker as well as without the use of a bifunctional linker. Quantum dot sensitized solar cells (QDSCs) are fabricated using Cu₂AgInS₄ QD sensitized porous TiO₂ NFs as the photoanode, Cu₂S as the counter electrode and polysulphide as the electrolyte, in order to study its photovoltaic performance. These results revealed that the QDs loaded onto the porous TiO₂ NFs using a bifunctional linker exhibits 27% improvement in the photoconversion efficiency of QDSC than that of the QDs loaded onto the porous TiO₂ NFs without the use of a bifunctional linker.