From Bottom to Top Interfaces and Layers: the Holistic Engineering Approach for Efficient, Stable and Large-Area n-i-p Structured Perovskite Solar Cells
Year: 2025
Type: dissertation
Abstract: Metal halide perovskites have emerged rapidly as promising materials for solar energy harvesting, with perovskite solar cell (PSC) power conversion efficiencies (PCEs) reaching 27%. Despite their excellent optoelectronic properties, low production cost, and facile up-scalability, the commercialization of perovskite solar modules (PSMs) still faces challenges in achieving long-term stable and large-area devices. This thesis focuses on optimizing the widely used n-i p architecture, where the bottom electron transport layer (ETL) is coated with the perovskite light-absorber, followed by a hole transport layer (HTL). For ensuring the stability of metal oxides layer used in HTL and ETL as bottom layers against the solution processed perovskite layer deposition, different metal oxides and perovskite compositions were well studied to understand and develop strategies for protecting the bottom metal oxide. To achieve a uniform large-area perovskite layer, the hybrid-chemical-vapor-deposition (HCVD) method was explored for perovskite film deposition. In addition, the perovskite seeding and coordination solvent engineering strategies were incorporated to improve crystallinity, facilitate the growth of larger grains, and promote the full conversion of the inorganic lead species during film growth. Furthermore, the HCVD method was extended to inorganic perovskite films. By using vapor amine molecules to mediate the formation of low-dimensional perovskite intermediate phases from CsPbI3, the crystallinity and orientation of CsPbI3 were enhanced, and it was scalable for fabricating large-area modules. A surface passivation strategy based on a hydrophobic molecule of perfluorobutanesulfonyl chloride (PFSC) was developed for CsPbI3-based PSMs, which passivates the perovskite surface, enhances interfacial contact with HTL, adjusts energy levels, and reduces surface defects, resulting in PSMs with a high certified efficiency and prolonged device operation lifetime. To further enhance PSM stability, the conventional 2,2’,7,7- tetrakis(N,N-di(4-methoxyphenylamine)-9,9’-spirobifluorene (spiro-OMeTAD, spiro) based HTL was modified. The commonly employed additive of lithium bis(trifluoromethane)sulfonimide (LiTFSI) was replaced by ammonia bis(trifluoromethane)sulfonimide (NH4TFSI), and a light-oxidation doping treatment was developed to improve the oxidation process in solution. This method avoids the time-consuming post-oxidation step in spiro-HTL in n-i-p devices. This study also examined the beneficial effects of TFSI salts in forming low-dimensional (2D) perovskite structures with enhanced thermal stability and prolonged device lifetime.
DOI: 10.15102/0002000985
Author: Zhang, Jiahao
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7110891993
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