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Quantum and Dielectric Confinement Effects in Lower-Dimensional Hybrid Perovskite Semiconductors
摘要： Hybrid halide perovskites are now superstar materials leading the field of low-cost thin film photovoltaics technologies. Following the surge for more efficient and stable 3D bulk alloys, multilayered halide perovskites and colloidal perovskite nanostructures appeared in 2016 as viable alternative solutions to this challenge, largely exceeding the original proof of concept made in 2009 and 2014, respectively. This triggered renewed interest in lower-dimensional hybrid halide perovskites and at the same time increasingly more numerous and differentiated applications. The present paper is a review of the past and present literature on both colloidal nanostructures and multilayered compounds, emphasizing that availability of accurate structural information is of dramatic importance to reach a fair understanding of quantum and dielectric confinement effects. Layered halide perovskites occupy a special place in the history of halide perovskites, with a large number of seminal papers in the 1980s and 1990s. In recent years, the rationalization of structure–properties relationship has greatly benefited from new theoretical approaches dedicated to their electronic structures and optoelectronic properties, as well as a growing number of contributions based on modern experimental techniques. This is a necessary step to provide in-depth tools to decipher their extensive chemical engineering possibilities which surpass the ones of their 3D bulk counterparts. Comparisons to classical semiconductor nanostructures and 2D van der Waals heterostructures are also stressed. Since 2015, colloidal nanostructures have undergone a quick development for applications based on light emission. Although intensively studied in the last two years by various spectroscopy techniques, the description of quantum and dielectric confinement effects on their optoelectronic properties is still in its infancy.
关键词： quantum confinement,multilayered perovskites,structural engineering,colloidal nanostructures,hybrid halide perovskites,optoelectronic properties,2D materials,dielectric confinement
更新于2025-09-23 15:23:52
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Alternative Type 2D-3D Lead Halide Perovskite with Inorganic Sodium Ions as Spacer for High Performance Light Emitting Diodes
摘要： Two-dimensional (2D) lead halide perovskites with long-chain ammonium halides display high photoluminescence quantum yield (PLQY), due to their size and dielectric confinement, which promise a high efficiency and low-cost light emitting diode (LED). However, the presence of insulating organic long-chain spacer cation (L) dramatically deteriorates the charge transport properties along the out-of-plane nanoplatelet direction or adjacent nanocrystals, which would limit the LED device performance. In order to overcome this issue, we successfully incorporate small alkaline ions such as sodium (Na+) to replace long organic molecule. Grazing incident X-ray diffraction (GIXRD) measurements verify the 2D layered formation with preferential crystallite orientation. In addition, the incorporated sodium salt also generates amorphous sodium lead bromide (NaPbBr3) in perovskite as spacers to form nanocrystal-like halide perovskite film. PLQY is dramatically improved in the sodium incorporated film associating with enhanced PL lifetime. With incorporating small concentration of an organic additive, this 2D-3D perovskite can achieve a compact and uniform film. Therefore, a 2D-3D perovskite achieves a high external quantum efficiency (EQE) of 15.9% with good operational stability. Our work develops a type of 2D-3D halide perovskite with various inorganic ions as spacers for high performance of promising optoelectronic devices.
关键词： two-dimensional,alkaline halide,perovskite,dielectric confinement,light-emitting diode
更新于2025-09-23 15:23:52
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Extremely reduced dielectric confinement in two-dimensional hybrid perovskites with large polar organics
摘要： Two dimensional inorganic–organic hybrid perovskites (2D perovskites) suffer from not only quantum confinement, but also dielectric confinement, hindering their application perspective in devices involving the conversion of an optical input into current. In this report, we theoretically predict that an extremely low exciton binding energy can be achieved in 2D perovskites by using high dielectric-constant organic components. We demonstrate that in (HOCH2CH2NH3)2PbI4, whose organic material has a high dielectric constant of 37, the dielectric confinement is largely reduced, and the exciton binding energy is 20-times smaller than that in conventional 2D perovskites. As a result, the photo-induced excitons can be thermally dissociated efficiently at room temperature, as clearly indicated from femtosecond transient absorption measurements. In addition, the mobility is largely improved due to the strong screening effect on charge impurities. Such low dielectric-confined 2D perovskites show excellent carrier extraction efficiency, and outstanding humidity resistance compared to conventional 2D perovskites.
关键词： dielectric confinement,humidity resistance,carrier mobility,exciton binding energy,2D perovskites
更新于2025-09-10 09:29:36