Wide range tuning of the size and emission color of CH3NH3PbBr3 quantum dots by surface ligands

Abstract

Organic-inorganic halide perovskite CH3NH3PbX3 (X= I, Br, Cl) quantum dots (QDs) possess the characters of easy solution-process, high luminescence yield, and unique size-dependent optical properties. In this work, we have improved the nonaqueous emulsion method to synthesize halide perovskite CH3NH3PbBr3 QDs with tunable sizes. Their sizes have been tailored from 5.29 to 2.81 nm in diameter simply by varying the additive amount of surfactant, n-octylamine from 5 to 120 μL. Correspondingly, the photoluminescence (PL) peaks shift markedly from 520 nm to very deep blue, 436 nm due to quantum confinement effect. The PL quantum yields exceed 90% except for the smallest QDs. These high-quality QDs have potential to build high-performance optoelectronic devices.

Deep Blue Layered Lead Perovskite Light‐Emitting Diode

“…This problem is particularly serious in the preparing deep blue PeLED device. 2) Perovskite quantum dot, [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44] a nano-sized perovskite encapsulated by a long chain of oleic acid, turns a large-scale crystal into a small quantum dot. For the quantum confinement effect, [45] the long chain conjugation of metal halide is inhibited, which shows a wide bandgap and high quantum efficiency of luminescence.…”

Ligand assisted swelling–deswelling microencapsulation (LASDM) for stable, color tunable perovskite–polymer composites

“…Long chain carboxylic acid and alkylamines are common choices of ligands employed in most solution syntheses of perovskite quantum dots, with organic acids always claimed to help with solvating precursors and providing colloidal stability while alkylamines are responsible for dimensional and size control. [25][26][27][28] With no need for colloidal stabilization in the in situ SDM process, it is questionable whether OAs play a critical role in LASDM. To investigate this, PPCs are synthesized without OAs (with alkylamines only).…”

“…Long chain alkylamines, such as octylamine (OcA) or oleylamine (OlA), and carboxylic acids,such as oleic acid, (OA) have been widely used as capping ligands in solution synthesis of PNCs, to help engineer the dynamics of crystallization, control the PNC size, coordinate surface sites and improve colloidal stability. [25][26][27] Here, ligands are applied in SDM to help with micelle formation during the swelling process, conne small PNC crystallization, and subsequently act as coordinators and stabilizers aer crystallization. As a result, PL efficiency is improved, and high PL quantum efficiency (PLQY) of larger than 70% can be achieved for PPCs with a wide range of optical densities (0.05-0.77) without concentration quenching.…”

Advances in metal halide perovskite lasers: synthetic strategies, morphology control, and lasing emission

“…Chen et al 66 fabricated CsPbBr 3 QDs with an average diameter from 7.1 to 12.3 nm by modifying the temperature, and the corresponding PL emission peaks could be tuned from 493 to 531 nm. Fang et al 67 synthesized MAPbBr 3 QDs with tunable average diameter from 2.82 to 5.29 nm by varying the additive amount of surfactant, and the corresponding PL emission peaks could shift from 436 to 520 nm due to the quantum confinement effect. Most recently, there have been much more researches about perovskite QDs by composition engineering for wider optoelectronic applications.…”