Role of Quantum Confinement in 10 nm Scale Perovskite Optoelectronics

Abstract

Quantum confinement-driven band structure engineering of metal halide perovskites (MHPs) is examined for realistically sized structures that consist of up to 10 5 atoms. The structural and compositional effects on band gap energies are simulated for crystalline CH 3 NH 3 PbX 3 (X = I/Br/Cl) with a tight-binding approach that has been well-established for electronic structure calculations of multimillion atomic systems. Solid maps of band gap energies achievable with quantum dots, nanowires, and nanoplatelets concerning sizes, shapes, and halide compositions are presented, which should be informative to experimentalists for band gap designs. The pathway to suppress band gap instability that appeared in mixed halide perovskites is proposed, revealing that the red shift induced by halide phase separation can be hugely diminished by reducing sizes and adopting halides of lower electronegativity. Our modeling results on finite MHP structures of over 10 nm dimensions show a blueprint for designs of stable lightemitting sources with precisely controlled wavelengths.

Influence of fumed silica and PMMA on optical properties of blue-emitting CH3NH3PbBr3 perovskite nanocrystals

“…Various chemical and physical approaches have been developed in recent years to fabricate the blue-emitting of OIHP based CH3NH3PbX3 [12]. Yadav et.…”

Enabling Large-Scale Simulations of Quantum Transport with Manycore Computing

“…In this work, we discuss several technical strategies for performance optimization of RGF-based NEGF simulations with the aid of manycore computing resources. Using our in-house code package, named the quantum simulation tool for advanced nanoscale device designs (QAND) [7,8], which employs tight-binding models for atomistic representation of semiconductor nanostructures [5,9] and has been actively being used for modeling studies of device designs with solid connections to experiments [10,11], we apply the strategies to our NEGF solver and rigorously conduct performance tests to understand how the applied technical strategies affect the performance in a single computing node that is equipped with a 64-core Intel Xeon Phi Knights Landing (KNL) processor [12] and two NVIDIA Quadro GV100 general-purpose graphic processing unit (GPU) devices [13]. In addition, in order to verify the ability of our NEGF solver to handle large-scale problems in huge computing environments, a strong scalability is tested in up to 2048 KNL nodes of the NURION supercomputer (the 21st fastest supercomputer in the world) [14], for end-toend simulations of quantum transport in a wide energy range.…”

Identification and Dynamics of Microsecond Long-Lived Charge Carriers for CsPbBr3 Perovskite Quantum Dots, Featuring Ambient Long-Term Stability

“…Halide perovskites with an ABX 3 structure (A = CH 3 NH 3 + , CH­(NH 2 ) 2 + , or Cs + ; B = Pb 2+ or Sn 2+ ; and X = Cl – , Br – , or I – ) have emerged as prominent materials for optoelectronic applications owing to their remarkable photophysical and electrical properties. These include a large absorption coefficient (∼10 4 –10 5 cm –1 ) across the visible to near-infrared spectrum, extended photoluminescence (PL) lifetimes, and high charge-carrier mobilities. , Distinctively, perovskite quantum dots (PeQDs) can modulate the energy gap through various compositions of A, B, and X elements while benefiting from quantum confinement effects. − Various synthesis methods for PeQDs have been developed, including hot injection, ultrasonication, and solvothermal synthesis . While the hot-injection technique is widely recognized for yielding PeQDs with high photoluminescence quantum yields (PLQY), , there is a growing preference for milder synthesis approaches, such as ligand-assisted reprecipitation (LARP) or emulsion synthesis routes, aiming at broader utility and commercial viability. − However, PeQDs produced via LARP or emulsion methods often exhibit lower PLQY, increased structural defects, and diminished photophysical stability .…”