Energy Transfer in Stability-Optimized Perovskite Nanocrystals

Abstract

Outstanding optoelectronic properties and a facile synthesis render halide perovskite nanocrystals (NCs) a promising material for nanostructure-based devices. However, the commercialization is hindered mainly by the lack of NC stability under ambient conditions and inefficient charge carrier injection. Here, we investigate solutions to both problems, employing methylammonium lead bromide (MAPbBr 3 ) NCs encapsulated in diblock copolymer core-shell micelles of tunable size.We confirm that the shell does not prohibit energy transfer, as FRET efficiencies between these NCs and 2D CsPbBr 3 nanoplatelets (NPLs) reach 73.6%. This value strongly correlates to the micelle size, with thicker shells displaying significantly reduced FRET efficiencies. Those high 2 efficiencies come with a price, as the thinnest shells protect the encapsulated NCs less from environmentally induced degradation. Finding the sweet spot between efficiency and protection could lead to the realization of tailored energy funnels with enhanced carrier densities for highpower perovskite NC-based optoelectronic applications.

Energy Funneling from Water-Dispersed Perovskites to Chromophores

“…We also observed an increase in the acceptor emission decay (Figure b). These observations can be accounted for by considering effective energy transfer from PNCs to RITC. − ,,, The kinetic parameters obtained upon triple-exponential fitting of all the PL decay profiles are summarized in Table S1. Among all five donor samples, the largest decrease in τ avg (∼58.3%) was seen for PNC-X1.…”

“…Fluorescence resonance energy transfer (FRET) is one such mechanism that describes the funneling of energy between two light-sensitive molecules . Therefore, employing PNCs in the fabrication of energy transfer assemblies might enable fine-grained regulation of energy flow. − …”

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

“…We provided a rationale to explain such distance-dependent FRET by considering the flexible behavior of NKE and their electrostatic interactions with RITC. Unlike previous studies elucidating a trade-off between ϕ FRET and water stability, this work presents a promising approach to optimize the excitation energy funneling from PNCs with adequate water stability . Our results can aid in the advancements of PNCs in moisture-resistant photovoltaics, light-harvesting assemblies, and optoelectronics as well as expand the field of cascade energy/charge transfer-mediated photocatalysis.…”

NondemandingIn SituEncapsulation Route to Ultrastable Perovskite Nanocrystals for White Light-Emitting Diodes

“…54,55 Moreover, macromolecule passivation, including polyimide, 56 polyacrylonitrile, 57 and polyfluorene suppressing the halide ion migration, 58 was found to be equally advantageous to enhancing PNC stability by suppressing the halide ion migration or forming coordination interaction for potential applications in CO 2 conversion, wide-color gamut displays, light-emitting diode (LED) devices, 59 and stretchable displays. 60,61 In addition to homopolymers, well-defined synthetic linear 61−64 and star-like block copolymers 65 with controlled molecular weight, pre-designed compositional architecture, and functionality were utilized to obtain highly stable PNCs owing to their ability to coordinate with surface atoms on PNCs to maintain colloidal stability, fill the traps to achieve the high PLQY, and form a condense protection shield on PNCs to maintain moisture stability. Apart from stability enhancing strategies via surface coating or surface ligand engineering, substitution of the A or B site element in the perovskite structure with dopants, 66,67 generation of a halide-rich surface, 68 and in situ formation in the natural product 69 were also proven to be effective for preserving perovskite phase stability and thermal stability without sacrificing the optical property, which were favorable to PNC-related devices requiring excellent charge-transport properties.…”

“…by constructing inert shielding on the surface of PNCs to prevent the perovskite crystal structure from being damaged by external perturbations and preserve optical properties. Surface-capping ligand engineering based on small molecules (e.g., semiconducting molecule, metal complex, organic sulfonium bromide, inorganic metal salt, and zwitterionic molecule) was identified as another efficacious approach for strongly anchoring on the PNCs to repair the surface defects of PNCs, thereby addressing the ligand thermodynamic instability issue of originally capped oleylamine (OAm) or oleic acid (OA) while increasing the various stabilities of PNCs (even in water) with high PLQY. , Although the stability of PNCs synthesized from this approach may not be as high as that of PNCs fabricated from inorganic coating strategies because PNCs were not fully covered by insulating ligands, a reasonable balance was made between the structural stability and electron/hole transportation property, which was essential for the high-performance PNC-based optoelectronics. , Moreover, macromolecule passivation, including polyimide, polyacrylonitrile, and polyfluorene suppressing the halide ion migration, was found to be equally advantageous to enhancing PNC stability by suppressing the halide ion migration or forming coordination interaction for potential applications in CO 2 conversion, wide-color gamut displays, light-emitting diode (LED) devices, and stretchable displays. , In addition to homopolymers, well-defined synthetic linear − and star-like block copolymers with controlled molecular weight, pre-designed compositional architecture, and functionality were utilized to obtain highly stable PNCs owing to their ability to coordinate with surface atoms on PNCs to maintain colloidal stability, fill the traps to achieve the high PLQY, and form a condense protection shield on PNCs to maintain moisture stability. Apart from stability enhancing strategies via surface coating or surface ligand engineering, substitution of the A or B site element in the perovskite structure with dopants, , generation of a halide-rich surface, and in situ formation in the natural product were also proven to be effective for preserving perovskite phase stability and thermal stability without sacrificing the optical property, which were favorable to PNC-related devices requiring excellent charge-transport properties.…”