Size dependent charge separation and recombination in CsPbI3 perovskite quantum dots

Abstract

CsPbI3 perovskite quantum dots (QDs) have shown great potential in light-harvesting and light-emitting applications, which often involve the transfer of charge carriers in and out of these materials. Here, we studied size-dependent charge separation (CS) and charge recombination (CR) between CsPbI3 QDs and rhodamine B (RhB) molecules, using transient absorption spectroscopy. When the average size decreases from 11.8 nm to 6.5 nm, the average intrinsic CS time constant decreases from 872 ± 52 ps to 40.6 ± 4.3 ps and the corresponding charge recombination time constant decreases from 3829 ± 51 ns to 1384 ± 54 ns. The observed trend of size-dependent CS and CR rates can be well explained by Marcus theory using the theoretically calculated CS and CR driving forces (ΔGCS and ΔGCR), molecular reorganization energy (λRhB), and electronic coupling strength between QD and RhB (HCS and HCR). Unlike the extensively studied more strongly quantum confined Cd chalcogenide QDs, the CsPbI3 QDs are in a weak quantum confinement regime in which size-dependent coupling strength plays a dominant role in the size-dependent charge transfer properties.

Lanthanide-doped inorganic halide perovskites (CsPbX3): novel properties and emerging applications

“…7(d-f). 103 Similar variations in absorption and emission spectra were also observed in CsPbBr 3 QDs and are indicated in Fig. 7(g).…”

State of the Art and Prospects for Halide Perovskite Nanocrystals

“…The electronic coupling of the QD and acceptor orbitals influences both charge separation and charge recombination dynamics. 933 It is shown that ∼99% photogenerated electrons can be transferred from CsPbI 3 NCs to TiO 2 , with a sizedependent rate ranging from 1.30 × 10 10 to 2.10 × 10 10 s −1 . 879 Scheidt et al investigated electron transfer between CsPbBr 3 NCs and several metal oxides such as TiO 2 , SnO 2 , and ZnO.…”

Perovskite Quantum Dots for Super‐Resolution Optical Microscopy: Where Strong Photoluminescence Blinking Matters

“…[77,78] Examples of efficient carrier scavengers, as already explored for catalysis or photovoltaic applications, include anthraquinones, [79] anthracene, [80] methyl viologen, [78,81] ferrocene, [82] and rhodamine molecules. [83] Optical spectroscopy studies employing perovskite QDs and surface-bound organic dyes showed that excitation energy transfer dominates over Förster resonance energy transfer. [84][85][86] PL intensity traces obtained at the single particle level demonstrated that excitation energy transfer from the QDs to acceptor molecules can efficiently suppress QD PL elongating the OFF-periods.…”

“…[84] Organic dyes that may act as excitation energy transfer acceptors for perovskite QDs include naphthalene and tetracene derivates, [85] various polycyclic aromatic hydrocarbons, [87] rhodamine B, [86] and perylene dyes. [88] In all these approaches, the transfer rates can be adjusted by the relative energy level alignment and the donor (QDs) [79,83,85,86,89] -acceptor (molecules) distance. [87,90,91] Additionally, active control of the emission dynamics could be obtained by employing a secondary control beam, which could facilitate/inhibit the electron/hole charge transfer process.…”