Efficient planar formamidinium-based perovskite solar cells
File(s)
Author(s)
Jiang, Zhongyao
Type
Thesis
Abstract
Organic-inorganic metal halide perovskites are receiving significant research attention as key materials for next-generation solar cells, owing to their excellent optoelectronic properties. Recent advancements in perovskite solar cells (PSCs) have resulted in unprecedented progress, with power conversion efficiencies (PCEs) approaching 26%. To further advance this cutting-edge technology, extensive strategies have been developed to improve the device performance. In addition to the pursuit of highly efficient PSCs through different approaches, this thesis also considers the long-term stability. In Chapter 1, an introduction to photovoltaic (PV) technology is presented. With traditional energy sources being limited and environmental concerns growing, renewable energy is urgently needed, and solar energy is a top alternative due to its abundant resources and cost-effectiveness. PSCs are considered as the next-generation solar cells because of their low cost, high efficiencies, and facile fabrication processes. Chapter 2 provides a literature review, including fundamentals from materials to devices, fabrication approaches, and foremost challenges. Chapter 3 demonstrates the experimental methods employed for materials characterization and device optimization, including thin film and device fabrication, structural, optical, energetic characterization, and stability analyses. Chapter 4 investigates the influence of the highest occupied molecular orbital (HOMO) of the hole transport layer (HTL) on the open-circuit voltage (VOC). The energetic offset between the HTL HOMO and the perovskite valence band (VB) is critical in determining the non-radiative recombination losses, which in turn affects the VOC losses. The stability studies show that FA-based perovskite is susceptible to degradation from light and moisture exposure, leading to the α-to-δ phase transition. In Chapter 5, a novel sequential dynamic deposition (SDD) approach with methylammonium chloride (MACl) treatment is introduced to fabricate perovskite films with a wide processing window, resulting in highly efficient formamidinium (FA)-based PSCs. In Chapter 6, outstanding results from previous chapters are summarized, and future perspectives are discussed.
Version
Open Access
Date Issued
2023-04-19
Date Awarded
01/02/2024
License URL
Advisor
McLachlan, Martyn
Heeney, Martin
Sponsor
China Scholarship Council
Publisher Department
Materials
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)