Fabrication and characterization of lead-free and lead based perovskite solar cells
File(s)
Author(s)
Min, Ganghong
Type
Thesis
Abstract
Lead halide perovskite has become the most promising materials for future photovoltaic application. However, the toxic of lead is the biggest obstacle for its further commercialization in the future. Recently, tin based perovskite is emerged as the best alternative to lead perovskite because it has shown the highest efficiency among all lead free perovskite. However, there is still a huge gap of the efficiency between Sn perovskite and lead perovskite. This thesis explores the engineering to boost the efficiency of Sn perovskite solar cell and investigate the factors which could affect the charge carrier dynamics and device performances by several characterizations.
Chapter 1 gives an introduction of solar energy and solar materials, with the development of solar materials from traditional materials to lead perovskite and tin perovskite. Chapter 2 introduce the experimental method used in this thesis, including device fabrication, materials characterization and optoelectronic characterizations.
Chapter 3 report the effect of the antisolvents for the device performance of 2D/3D Sn perovskite solar cell. This chapter found that antisolvent can modulate the distribution of the 2D phase in perovskite film and the relationship between 2D phase distribution and device performance are investigated. Chapter 4 attempts to study the effects of hole transport layers on device performance of Sn perovskite. In the first part, both compact and mesoporous NiO are employed as hole transport layer for Sn perovskite but the device fails to work, suggesting the poor contact between NiO and Sn perovskite, which needs further optimizations. The second part moves back to PEDOT: PSS, studying the effects of dedoping by introducing ammonia on device performances. The better film stability and improved VOC are obtained but the origin of it is still not clear. Future study should be targeted on the charge recombination dynamics which is highly related to Voc loss.
Halide composition engineering is also a promising method to improve the device performance and stability but the insights about it are not clear. The chapter 5 moves back to lead perovskite and study the effects of bromide substitution on device performances. It is found that the Br substitution can enhance the VOC with the increased crystallinity and prolonged photoluminescence lifetime. By using novel pump-push-photocurrent spectroscopy, the charge carriers dynamics of trap sates are studied, which play a crucial role to suppress the VOC loss. This work provides an understanding of the halide engineering in Sn perovskite, which could be helpful for similar work in Sn perovskite.
Finally, chapter 6 summarizes the conclusions of all work and discuss the perspective of the future works based on this thesis.
Chapter 1 gives an introduction of solar energy and solar materials, with the development of solar materials from traditional materials to lead perovskite and tin perovskite. Chapter 2 introduce the experimental method used in this thesis, including device fabrication, materials characterization and optoelectronic characterizations.
Chapter 3 report the effect of the antisolvents for the device performance of 2D/3D Sn perovskite solar cell. This chapter found that antisolvent can modulate the distribution of the 2D phase in perovskite film and the relationship between 2D phase distribution and device performance are investigated. Chapter 4 attempts to study the effects of hole transport layers on device performance of Sn perovskite. In the first part, both compact and mesoporous NiO are employed as hole transport layer for Sn perovskite but the device fails to work, suggesting the poor contact between NiO and Sn perovskite, which needs further optimizations. The second part moves back to PEDOT: PSS, studying the effects of dedoping by introducing ammonia on device performances. The better film stability and improved VOC are obtained but the origin of it is still not clear. Future study should be targeted on the charge recombination dynamics which is highly related to Voc loss.
Halide composition engineering is also a promising method to improve the device performance and stability but the insights about it are not clear. The chapter 5 moves back to lead perovskite and study the effects of bromide substitution on device performances. It is found that the Br substitution can enhance the VOC with the increased crystallinity and prolonged photoluminescence lifetime. By using novel pump-push-photocurrent spectroscopy, the charge carriers dynamics of trap sates are studied, which play a crucial role to suppress the VOC loss. This work provides an understanding of the halide engineering in Sn perovskite, which could be helpful for similar work in Sn perovskite.
Finally, chapter 6 summarizes the conclusions of all work and discuss the perspective of the future works based on this thesis.
Version
Open Access
Date Issued
2023-04-17
Date Awarded
01/07/2023
Advisor
Haque, Saif
Publisher Department
Chemistry
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)