Fundamental Study of Solution Processed Inorganic and Hybrid Thin Film Solar Cells

摘要

Solar energy is inexhaustible. It’s effective and widespread utilization is the way to prevent the Earth from being further polluted. Solar cell has been demonstrated to be the most promising technology to produce electricity by absorbing sunlight, with crystal silicon (c-Si) solar cell leading the market. However, significant amount of energy is required for manufacturing of crystal silicon solar cells because of vacuum-based fabrication process and high consumption of raw materials. ud Solution processed thin film solar cells have been considered as promising alternatives to c-Si solar cells because of the low-cost process and low consumption of raw materials. In this work, two types of thin film solar cells (TFSCs), namely Cu2ZnSnS4 (CZTS) and CH3NH3PbI3 (MAPbI3) have been explored with a focus on the fabrication and characterization. In the case of CZTS TFSCs, a promising efficiency of 6.2% has been obtained by modifying a water-based process previously developed. In the case of MAPbI3 TFSCs, an efficiency of 15.39% has been achieved from a spin-coating process. By incorporating with Cl into MAPbI3 thin film, the efficiency was significantly increased to 18.60%. To improve the stability of MAPbI3 TFSCs, a device structure incorporating inorganic metal oxides as charge transport layers (CTLs) has been developed. A promising result with a highly stable and a highly efficient perovskite solar cell was obtained.ud The mechanisms behind the improvement were revealed by open-circuit voltage decay (OCVD) measurement, admittance spectroscopy (AS), temperature-dependent open-circuit voltage (VOC), and Kelvin probe force microscopy (KPFM). By comparing the device properties of CZTS solar cells and MAPbI3 solar cells, it was found that the interfaces of these two types of solar cells were crucial in improving their efficiencies. Therefore, interface engineering should be prioritized to further improve the efficiencies of these two PV technologies.