Photon-Induced Electron Transfer in Ligand-Stabilized Monoclinic CsPbBr₃ and Alanine-Functionalized Graphene Heterostructures

Abstract

In the field of catalysis and energy applications, heterostructures of halide perovskite nanocrystals (NCs) and functionalized graphene are emerging as promising materials. In such heterostructures, it is critical to gain insights into the knowledge that governs the charge and energy transfer dynamics between the components of the heterostructures because it directly affects the efficiency of devices. In this work, we present heterostructures that consist of mercaptoacetic acid (MAA)-functionalized CsPbBr 3 NCs and alanine-functionalized graphene. The surface functionalization of CsPbBr 3 NCs and graphene enables an effective attachment of the NCs and graphene. The use of MAA as a functionalizing ligand not only passivates the surface of NCs but also provides the possibility of tuning the size of NCs and further coupling with alanine-functionalized graphene. Varying the amount of MAA allows us to synthesize the brightest CsPbBr 3 NCs with an absolute photoluminescence quantum yield (PLQY) of 49% and an emission spectral width of 25 nm. By combining alanine-functionalized graphene, the photoluminescence (PL) quenching of the NCs is observed. The photoexcited electron transfer from NCs to alanine-functionalized graphene is responsible for the occurrence of PL quenching that is advocated by time-resolved photoluminescence (TRPL) studies and cyclic voltammetry (CV) analysis. Our work provides a method to control the energetics and analyze the types of charge transfer in functionalized perovskite NCs and graphene heterostructures and motivates further research about the basic knowledge of charge transfer in functionalized donor−acceptor heterostructures.

Photo-driven electron transfer from FAPbBr3 perovskites nanocrystals to photodeactivatable 4-(phenylazo) benzoic acid

“…The following equations were used to calculate the experimental electrochemical LUMO level in eV units: 59 E (LUMO) = − e [ E onset red + 4.4] E (HOMO) = [ E LUMO − E 0 – 0 ]where E 0 – 0 energy is the 0–0 energy calculated from UV-vis and fluorescence emission spectra.…”

Stable, Scalable, and Free-Standing Perovskite Quantum Dots Composite Reinforced by Cellulose Fibers

“…As shown in Figure S2, the PQDs fabricated here demonstrate 4f 7/2 and 4f 5/2 peaks for Pb at 138.5 and 143.2 eV, which are lower than those of normal CsPbBr 3 or MAPbBr 3 perovskites. 38,39 The negative shift implies that the electron affinity of Pb atoms was weakened by the complexation effect that occurred between cellulose and Pb 2+ . This interaction between the hydroxyl groups and Pb 2+ of the [PbBr 6 ] 4− cage is illustrated in Scheme S1.…”

Tuning charge transfer efficiency by functionalizing ligands in FAPbBr3 nanocrystals and graphene heterostructures

“…The PL spectra and PL decay kinetics were analyzed using Pico-Quant Fluo Time 300, FT-300, steadystate and time-resolved fluorescence spectrometer that operated on the principle of time-correlated single photon counting (TCSPC) technique, as described previously. 51,52 The PL spectra and kinetics were recorded after excitation at 306 nm with a pulsed LED excitation source in toluene solvent at room temperature. Cyclic voltammograms (CVs) for NCs and functionalized graphene were recorded by the CH1660B electrochemistry workstation.…”