Electronic and Optical Properties of Ultrasmall ABX₃ (A = Cs, CH₃NH₃/B = Ge, Pb, Sn, Ca, Sr/X = Cl, Br, I) Perovskite Quantum Dots

Abstract

Perovskite quantum dots (QDs) constitute a novel and rapidly developing field of nanotechnology with promising potential for optoelectronic applications. However, few perovskite materials for QDs and other nanostructures have been theoretically explored. In this study, we present a wide spectrum of different hybrid halide perovskite cuboid-like QDs with the general formula of ABX 3 with varying sizes well below the Bohr exciton radius. Density functional theory (DFT) and time-dependent DFT calculations were employed to determine their structural, electronic, and optical properties. Our calculations include both stoichiometric and nonstoichiometric QDs, and our results reveal several materials with high optical absorption and application-suitable electronic and optical gaps. Our study highlights the potential as well as the challenges and issues regarding nanostructured halide perovskite materials, laying the background for future theoretical and experimental work.

Structural and Electronic Properties of Small Perovskite Nanoparticles of the Form ABX3 (A = MA, DEA, FA, GA, B = Pb, Sn, X = Cl, Br, I)

“…At this point, it should be noted that the adopted functional is a standard GGA one, which suffers from the well known and well documented HOMO-LUMO gap underestimation problem. In the specific type of nanoparticle, it has been shown that the PBE values can be underestimated by as much as 1.5 eV compared to the more accurate and reliable hybrid PBE0 ones [42]. The produced PDOS diagrams for 3 × 3 × 3 NPs are presented in Figure 3 in a 4 × 6 array with each line corresponding to a different type of A cation and each column to a different backbone structure.…”

“…In Ref. [42], an extended study on the properties of both CsBX 3 and MABX 3 QDs in the form of cuboids has been presented where B was a divalent cation (Ge,Sn, Pb, Ca or Sr) and X a halogen atom (Cl, Br or I). In that reference, both stoichiometric and pseudohydrogen passivated non-stoichiometric structures were considered, and it was found that the single particle and optical gaps decreased with the halogen's atomic number.…”

Crystal‐Size‐Induced Band Gap Tuning in Perovskite Films

“…Previous DFT calculations on small nanocrystallites have investigated the dependence of the band gap on their size [23] without distinguishing between structural effects and QC.W e find that anarrower band gap is associated with alarger a max , i.e., less tilted structures,a nd lower r Pb max ,i .e., lower Pb offcentering.T hus,s imulations predict that surface-induced structural effects produce as hift in the PL spectra of ca. 13 nm towards longer wavelengths between ac a.…”

Electronic structure transition of cubic CsSnCl3 under pressure: effect of rPBE and PBEsol functionals and GW method

“…To resolve the problem, however, researchers are searching for air and moisture stable materials with useful properties in the required surrounding conditions. Some perovskites are air and moisture stable with useful physical properties for solar cell applications [ 1 , 2 ]. Besides, these compounds show insulator, conductor, semiconductor, and superconductor properties as well [ 1 , 2 ].…”

“…Some perovskites are air and moisture stable with useful physical properties for solar cell applications [ 1 , 2 ]. Besides, these compounds show insulator, conductor, semiconductor, and superconductor properties as well [ 1 , 2 ]. They have noteworthy physical properties including optical, charge ordering, magnetic, useful spin-dependent electronic transport, good thermoelectric performance, high magnetoresistance, and ferroelectric properties [ 3 , 4 , 5 , 6 , 7 ].…”