Study on optimization and characterization of perovskite (MAPbI3) solar cells : Solution & Evaporation method

다국어 초록 (Multilingual Abstract)

The materials which have perovskite structure, known as “perovskite materials”, have been studied steadily and spread them out various fields of research, e.g., Solar Cells, TFTs, Quantum Dots (QD) devices. This research treated the Perovskite (Methylammonium Lead Iodide (CH3NH3PbI3)) based solar cells among them and focused on optimization & characterization of them by solution & evaporation method.
In this report, two processes (one is a solution, the other is an evaporation process) of deposit perovskite thin films will be introduced respectively. The general process in the research fields uses the solution process. Then, there are already lots of well-known factors for controlling the parameters of perovskite layers, e.g., Concentration of solutions and spin speed which is mostly related to the thickness of the samples, Solution treatment (ex. Toluene) and annealing temperature & time after spin coating that helps to make high-quality of crystallization. Based on them, this study focused on the effect of solution temperature before spin coating on the performance of perovskite solar cells. The perovskite solutions, dissolved during more than 4 hours before spin coating with different temperature from room temperature (RT) to 90°C, were used.
For making a Photovoltaic device, the large size of the panel is prerequired, and it indicates that the uniformity of samples is one of the essential factors. The evaporation process is an adaptable one for enhancing it. In this work, the many factors for optimization of perovskite thin films as well as electron transport layer (ETL) and hole transport layer (HTL) were treated. The ratio of Methylammonium Iodide (MAI) to Lead(II) Iodide (PbI2), the evaporation speed, and annealing condition are for perovskite layer. Also, for two transport layers, Methanol treatment and annealing condition (on the PEDOT:PSS layer (HTL)) and concentration solution, spin coating speed (on the PC60BM layer (ETL)) were studied.
Both Perovskite solar cells used two different processes consist of same structure such as Glass / ITO (anode) / PEDOT:PSS (HTL) / CH3NH3PbI3 / PC60BM (ETL) / Al or Au (Cathode). The various measuring instruments, e.g., visible-ultraviolet (UV) spectrophotometer, X-ray Diffraction (XRD), contact angle, profilometer (α-step), Scanning Electron Microscope (SEM),, and solar simulator, were used for analyzing both electrical and optical characteristics of perovskite thin films & Solar cells. Then, from these characterizations, the optimization of perovskite solar cells will be shown in this report.

목차 (Table of Contents)

• 1. Introduction 1
• 1.1. Broad concept of solar cells 1
• 1.2. Operating principle of Solar Cells 2
• 1.3. Electrical characteristics of Solar Cells 4
• 1.4. Perovskite Solar cell 12
• 2. Experimental Section 15
• 2.1. Solution Perovskite-based Solar Cells 15
• 2.2. Evaporation Perovskite-based Solar Cells 17
• 3. Results and discussion 23
• 3.1. Solution Perovskite-based Solar Cells 23
• 3.1.1. Perovskite (CH3NH3PbI3) materials characteristics 23
• 3.1.2. Perovskite (CH3NH3PbI3) Photovoltaic characteristics 29
• 3.2. Evaporation Perovskite-based Solar Cells 30
• 3.2.1. Optimization of the Perovskite-based thin film 30
• 3.2.2. Enhance the perovskite devices quality 39
• 4. Conclusion 50
• Acknowledgements 52
• Reference 52