Simultaneous Interface Amelioration and Energy Level Modulation Using In Situ Polymerized Molecules for Efficient and Stable Perovskite Solar Cells

Abstract

Charge accumulation and charged defects at both bulk and buried heterojunction interfaces of perovskites are primarily related to the photovoltaic performance and shelf stability of perovskite solar cells (PSCs). Moreover, detrimental defects distributing along the perovskite bottom side in contact with the tin oxide (SnO2) surface may exert unparalleled significance in charge extraction and transport. Most importantly, interfacial nonradiative recombination can also widely exist, which will seriously hamper efficiency of the related device. In this work, a multifunctional chemical bridge at the perovskite/SnO2 interface is devised through triggering an in situ polymerization strategy, by which cross-linked polymerizable 3-(trimethoxysilyl)propyl methacrylate (MAPS) monomers under the combination of temperature and initiators can form bulkier macropolymers (MAPS dimers). Detailed theoretical and experimental results reveal that the carbonyl groups (CO) of both MAPS monomers and MAPS dimers can chemically anchor to perovskite bottom side through a CO···Pb coordination bond interaction to regulate the film quality and the siloxane groups effectively couple with oxygen vacancies on the SnO2 film surface to facilitate its optoelectronic properties. Compared with the primitive MAPS monomer units, the resultant MAPS dimers simultaneously prevent interfacial charge accumulation and demonstrate a more benign energy level alignment to further augment photovoltaic performance of PSCs. Thus, the devices assembled under open-air conditions based on double-sided passivation deliver a decent photoelectronic performance with the champion efficiency of 20.94% accompanied by negligible hysteresis. Meanwhile, the unencapsulated targeted devices maintain 93.1% and 86.5% of their original efficiency after continuous 500 h thermal treatment and 500 h light illumination under open-circuit conditions, respectively.

Natural Chelating Agent-Treated Electron Transfer Layer for Friendly Environmental and Efficient Perovskite Solar Cells

“…30 Moreover, Xiong et al used the MAPS monomer in situforming polymer to form a chemical bridge to passivate the uncoordinated Pb 2+ and vacancy oxygen at the perovskite and ETL interface, thus optimizing the energy level structure and reducing the interface charge accumulation, and obtained a PCE of 20.94%. 31 Li et al used methoxyamine hydrochloride (MOACl) as a passivator for SnO 2 ETLs in PSCs. MOACl improves the film quality of SnO 2 , boosting the overall PCE of the cells to 24.34%.…”

“…Many kinds of materials have been employed to passivate the SnO 2 ETL defects, including organic molecular materials, inorganic salts, metal oxides, multifunctional composites, and ionic liquids. − For example, Liu et al introduced hydroxy-containing EDTA-2 M into SnO 2 precursor solution, and the uncoordinated Sn 4+ trap defects of ETL were significantly passivated by −CO of EDTA-2M, greatly improving the electron mobility and leading to an enhanced PCE of 23.7% . Moreover, Xiong et al used the MAPS monomer in situ-forming polymer to form a chemical bridge to passivate the uncoordinated Pb 2+ and vacancy oxygen at the perovskite and ETL interface, thus optimizing the energy level structure and reducing the interface charge accumulation, and obtained a PCE of 20.94% . Li et al used methoxyamine hydrochloride (MOACl) as a passivator for SnO 2 ETLs in PSCs.…”