Thesis presented February 09, 2022

Abstract:
Chapter 1 briefly introduces the background and status of current photovoltaic research, and clarifies the purpose of this work. Then the basic principles of photovoltaics are introduced in detail. The characteristics of organic and inorganic lead halide perovskite materials and charge transport materials that constitute perovskite solar cells are also discussed. As the background of the subsequent chapters, this chapter briefly introduces the structure, stability and hysteresis problems of perovskite solar cells.
Chapter 2 introduces the new thin film deposition technology (under the background of manufacturing perovskite solar cells) and the characterization technology applied to perovskite active materials and charge transport layers. The work in the remaining chapters mainly relies on the J-V scanning of perovskite solar cells, which will be described in Chapter 1. The combined use of J-V scanning and microscope, and spectroscopy provides guidance for optimizing perovskite solar cells.
Chapter 3 discusses the use of composition optimization engineering to introduce excess PbI₂ and MACl (to be presented in Chapter 1) in the perovskite precursors to maximize the performance of perovskite solar cells. Subsequently, we developed a simple hole transport layer passivation material to fix the contact problem at the interface and to increase the crystallinity of the perovskite crystals. The introduction of passivation layer not only improved the FF of the solar cell to a great extent, but also effectively improved the stability of the perovskite solar cell under humid atmosphere.
Chapter 4, a novel thin film deposition method, Electrostatic Spray Deposition (ESD), is presented to prepare charge transport layers. This method brings better surface morphology and denser Cu:NiO films than the conventional spin-coating method. By varying the parameters such as temperature and deposition time, we obtained uniform dense Cu:NiO thin films. The application of this film to perovskite solar cells can effectively improve the performance of solar cells with favorable FF. In addition, this approach allows the use of different ions for the doping of NiO, such as Li.
Chapter 5 describes a method for the synthesis of NiO nanoparticles. The preparation of the hole transport layer in Chapter 3 and 4 requires high temperature processing, which can limit the application of this NiO hole transport layer. In this chapter, ultra-small NiO nanoparticles are synthesized by trying different synthetic routes. The size of the nanoparticles is well controlled and has an excellent particle size distribution. The NiO nanoparticles show potential for application in all-inorganic charge transport layer perovskite solar cell devices.

Keywords:
thin films, solar cells, nanoparticles

On-line thesis.