Binding Strength-Guided Shuttling of Charge Carriers from Perovskite Nanocrystals to Molecular Acceptors

Abstract

Efficient charge extraction in lead halide perovskite nanocrystals is frequently sought-after and probed using various probe molecules. Often ignored, the chemical bonding of the molecules to the perovskite’s surface, as dictated by the terminal anchoring functional group, can have implications on the excited-state interactions between perovskite nanocrystals and the charge-shuttling molecules. Considering the remarkability of the recent work on ferrocene-based molecules in allowing charge transfer in perovskite nanocrystals, we have employed ferrocene molecule functionalized with various functional groups to understand the binding and charge-transfer process at the interface of the perovskite nanocrystal and the redox relay molecule. We evidenced that the charge transfer enhanced with enhancement in binding, as validated by the association constant evaluated as high as 1.71 × 107 M–1. In particular, the −COOH and −NMe2 functional groups led to the efficient quenching of photoluminescence (PL) emission and a decrease in photoluminescence lifetime than the other functional group analogues, showing their feasibility in charge transfer studies. More importantly, the −NMe2 functional group indicated passivation of the defects on the perovskite surface, attributed to the interaction between the lone pair of nitrogen and the undercoordinated surface Pb2+ cations. This was also evident in the transient absorption spectra, where the excited-state interaction could be analyzed better. This work opens avenues for exploring anchoring moieties in facilitating charge transfer across the perovskite interface, thus impacting its photocatalytic applications.

Extending Infrared Emission via Energy Transfer in a CsPbI3–Cyanine Dye Hybrid

“…The linear relationship between 1/(ϕ 0 – ϕ obs ) and 1/[IR125] as shown in Figure D yields (see the Supporting Information for the analysis) an apparent association constant ( K app ) of 2 × 10 5 M –1 for the binding of IR125 with CsPbI 3 . Such a high K app is indicative of a strong binding of the acceptor dye to the surface of the nanocrystal. − As discussed in the previous studies, strong binding of the dye to the semiconductor NC is an essential criterion to observe singlet and triplet energy transfer.…”

Enhanced Stability and Energy Transfer in Perovskite Nanocrystals: Paving the Way for Moisture-Resistant Light-Harvesting Devices

“…Perovskites have emerged as promising materials for photovoltaics, optoelectronics, photodetectors, and photocatalysis due to their high power conversion efficiency (PCE), low fabrication cost, and ease of processing. − Their intriguing attributes, such as tunable and broad visible-light absorption, high absorption cross section, high photoluminescence quantum yield (PLQY), high defect tolerance, low excitonic binding energies, and long charge carrier diffusion length, make them ideal for light-harvesting applications. The optical properties of perovskite nanocrystals (PNCs) can be tuned by modulating their morphology or halide composition. − Morphology influences the quantum confinement effect, providing opportunities to regulate excited-state dynamics. − Understanding surface chemistry is essential for regulating the properties of PNCs, offering exciting prospects for researchers to unlock their full potential. − Surface capping ligands, such as oleic acid (OA) and oleylamine (OAm), play a pivotal role in controlling surface chemistry and morphology.…”

CsPbBr3 Nanocrystals as Efficient Photocatalysts for Dehydrohalogenation: Toward Environmentally Friendly Trichloroethylene Synthesis

“…However, this also limits their stability in polar solvents, initiating research-based efforts to enhance the photocatalytic activity while maintaining the operational stability. ,− Great strides in organic photocatalysis have been made using halide perovskites, such as C–C, , N–N, C–O, and C–S bond formations. − Similarly, reports have witnessed bond activation strategies, particularly the C–X bond activation in alkyl halides during the photoassisted anion-exchange reaction in perovskites. , Following this thought process, we devised a C–X bond activation strategy using cesium lead halide-based perovskites, CsLHPs (CsPbX 3 , X = –I, –Cl, and –Br). Under benign conditions, a dehydrohalogenation reaction was carried out to synthesize trichloroethylene (TCEt) from 1,1,2,2-tetrachloroethane (TCE) via a photocatalytic pathway.…”