Dodecahedron CsPbBr₃ Perovskite Nanocrystals Enable Facile Harvesting of Hot Electrons and Holes

Abstract

This Letter reports the facile harvesting of hot carriers (HCs) in a composite of 12-faceted dodecahedron CsPbBr 3 nanocrystal (NC) and a scavenger molecule. We recorded ∼3.3 × 10 11 s −1 HC cooling rate in NC when excited with ∼1.4 times the band gap energy (E g ), increasing to >3 × 10 12 s −1 in the presence of scavengers at high concentration due to the HC extractions. Since the observed intrinsic charge transfer rate (∼1.7 × 10 12 s −1 ) in our NC− scavenger complex is about an order of magnitude higher than the HC cooling rate (∼3.3 × 10 11 s −1 ), carriers are harvested before their cooling. Further, a fluorescence correlation spectroscopy study reveals NC tends to form a quasi-stable complex with a scavenger molecule, ensuring charge transfer completed (τ ct ≈ 0.6 ps) much before the complex breaks apart (>600 μs). The overall results of our study highlight the promise shown by 12-faceted NCs and their implications in modern applications, including hot carrier solar cells.

Electron Transfer from an Optically Pumped Polyhedral Perovskite Nanocrystal to Pristine Fullerene

“…The HRTEM image confirms the dodecahedron morphology of our PNCs, resembling previous reports. ,− The inset shows the particle size distribution, with an average edge length of ∼18 nm (Figure A). Powder XRD patterns depicted in Figure B reveal the presence of (112) and (200) facets, matching nicely with PDF reference lines for the orthorhombic phase (PDF-01-072-7929) and the previous reports. ,, Steady-state PL and UV–vis spectra of our 12-faceted PNCs exhibit peaks at ∼518 and ∼510 nm (first excitonic), respectively; both are slightly red-shifted compared to ones (∼515 and ∼504 nm) reported for cubic counterparts of similar size (Figure C). ,, …”

“…Powder XRD patterns depicted in Figure 1B reveal the presence of ( 112) and (200) facets, matching nicely with PDF reference lines for the orthorhombic phase (PDF-01-072-7929) and the previous reports. 1,20,21 Steady-state PL and UV−vis spectra of our 12-faceted PNCs exhibit peaks at ∼518 and ∼510 nm (first excitonic), respectively; both are slightly red-shifted compared to ones (∼515 and ∼504 nm) reported for cubic counterparts of similar size (Figure 1C). 1,22,23 Instruments Used.…”

“…Interference from solvent diffusion often complicates the solution phase PET study. However, the present study involves PNC–fullerene complex formation, as confirmed by the fluorescence correlation spectroscopy (FCS) study, where the observed PET time scale at high quencher concentration is purely intrinsic. − …”