Charge Transport between Coupling Colloidal Perovskite Quantum Dots Assisted by Functional Conjugated Ligands

Abstract

Long alkyl-chain capping ligands are indispensable for preparing stable colloidal quantum dots. However, its insulating feature blocks efficient carrier transport among QDs, leading to inferior performance in light-emitting diodes (LEDs). The trade-off between conductivity and colloidal stability of QDs has now been overcome. Methylamine lead bromide (MAPbBr ) QDs with a conjugated alkyl-amine, 3-phenyl-2-propen-1-amine (PPA), as ligands were prepared. Owing to electron cloud overlapping and the delocalization effect of conjugated molecules, the conductivity and carrier mobility of PPA-QDs films increased almost 22 times over that of OA-QD films without compromising colloidal stability and photoluminescence. PPA-QDs LEDs exhibit a maximum current efficiency of 9.08 cd A , which is 8 times of that of OA-QDs LEDs (1.14 cd A ). This work provides critical solution for the poor conductivity of QDs in applications of energy-related devices.

Recent advances and prospects toward blue perovskite materials and light‐emitting diodes

“…Surface defects of perovskites form nonradiative recombination centers, which can increase the probability of nonradiative recombination. The passivation of surface defects of perovskites using organic and/or inorganic ligands (eg, didodecyldimethylammonium bromide (DDAB), trimethylammonium (TMA), iso‐propylammonium (IPA), trioctylphosphine oxide (TOPO), 3‐phenyl‐2‐propen‐1‐amine (PPA), PbX 2 , ZnX 2 , CdX 2 , MnX 2 , and SnX 2 ) will reduce surface defects and increase the radiative recombination. In addition, the doping of B‐sites (Mn 2+ , Ce 3+ , Sn 2+ , Sr 2+ ) can increase the PLQYs of the perovskite and improve the efficiency and stability of the device.…”

Conjugated Alkylamine by Two‐Step Surface Ligand Engineering in CsPbBr3 Perovskite Nanocrystals for Efficient Light‐Emitting Diodes

“…Recently, An organic conjugated molecule, 3‐phenyl‐2‐propen‐1‐amine (PPA), act as capped ligand was used in preparing methylammonium lead bromide (MAPbBr 3 ) NCs. Significantly, the carrier mobility of the MAPbBr 3 NCs films as well as the performance of the resulting electroluminescence devices are significantly improved . In their report, the density of PPA in the MAPbBr 3 NCs was limited by synthesis process based on the ligands‐assisted re‐precipitation (LARP) technique .…”

“…Meanwhile, k nr decreased from 0.027 ns −1 (0.0 PPA) to 0.012 ns −1 (0.25 PPA), suggesting that the nonradiative decay is suppressed by the incorporation of PPA during the process of synthesis. The promotional PLQY and time‐resolved PL decay indicate that the introduction of PPA effectively reduces the trap states owing to the less steric hindrance compared to the long chain alkyamine (OLA), more flexibility and freedom, can passivate the defects which the long chain alkyamine cannot reach, and spontaneously inhibit the non‐radiative recombination …”

Post‐Treatment Engineering of Vacuum‐Deposited Cs2NaBiI6 Double Perovskite Film for Enhanced Photovoltaic Performance

“…The research of a thin‐film photovoltaic device based on a hybrid organic–inorganic lead (Pb) halide perovskite material has been significantly progressed during the last decade, and the world record power conversion efficiency (PCE) has recently reached 24.2% . The promising performance of perovskite solar cells (PSCs) is already competitive with CdTe and polycrystalline silicon‐based solar cells .…”