A Multi-functional Molecular Modifier Enabling Efficient Large-Area Perovskite Light-Emitting Diodes

Abstract

We developed a molecular interface control strategy that eliminates pinholes in perovskites by controlling the dynamics of film formation. The approach simultaneously passivates defects in perovskites by incorporating Br. As a result, the strategy prevents both shorts and non-radiative recombination, all the while providing improved charge injection and balanced charge transport. These improvements enable a 20 mm 3 20 mm perovskite LED with an external quantum efficiency of over 16%, the record efficiency for large-area perovskite electroluminescent devices.

Halide Perovskite Nanocrystal Emitters

“…[ 208 ] Wang et al studied the multifunction of the molecular interface (1,3,5‐tris (bromomethyl) benzene (TBB))) control approach that reduces pinholes in the large‐area perovskite layers, by controlling the film formation, and simultaneously passivates the defects in perovskites by incorporating Br species. [ 209 ] This approach prevents both shorts and nonradiative recombination, leading to improved charge injection or transport of PeQLEDs. [ 209 ] The green FAPbBr 3 nanocrystal PeLED, fabricated with a multifunctional molecular interface modifier, displayed a EQE of 20.1%.…”

“…[ 209 ] This approach prevents both shorts and nonradiative recombination, leading to improved charge injection or transport of PeQLEDs. [ 209 ] The green FAPbBr 3 nanocrystal PeLED, fabricated with a multifunctional molecular interface modifier, displayed a EQE of 20.1%. [ 209 ] The selection of interfacial layer materials is vital for obtaining a high‐performance PeQLED.…”

Efficient wide-bandgap perovskite solar cells enabled by doping a bromine-rich molecule

“…It is evident that the binding energy peaks of Pb 4f and Br 3d at 68.3 eV (Br 3d 5/2 ) and 69.35 eV (Br 3d 3/2 ) for the perovskite with 0.3% TBB shift to lower positions, while the binding energy peaks of I 3d5 and Cs 3d5 remain almost unchanged. We attribute the shifts to the doping of TBB into the wide-E g FA 0.8 Cs 0.2 PbI 2.1 Br 0.9 perovskite and also more electronegative Br − in TBB molecules [33,35]. Moreover, Br − in TBB molecules may partially compensate the I − vacancies arising from the evaporation during the thermal annealing process.…”

“…All TBB-incorporated films have prolonged average carrier lifetimes compared with the pristine one, in which the perovskite with 0.3% TBB exhibits the longest carrier lifetime of 668 ns, 1.5 times longer than the control one (414 ns). These results indicate that TBB molecules effectively passivate the defects at the grain boundaries of wide-E g perovskite due to the large amount of grains, leading to suppressed nonradiative recombination loss [33]. To clarify the effects of TBB on the electrical properties and chemical states of the perovskite absorber, we carried out XPS measurement to evaluate the interaction between TBB and other elements.…”

“…A halide-rich nature with a benzene ring structure of 1,3,5-tris (bromomethyl) benzene (TBB) is typically used in chemical synthesis as an initiator or intermediate, by which high-quality CsPbBr 3 perovskite nanocrystals have been prepared [30][31][32]. Wang et al have employed TBB to modify the hole transport layer and achieved a high external quantum efficiency (EQE) of green perovskite nanocrystal light-emitting diodes [33]. Herein, we use a Brrich small molecule TBB as an additive into perovskite precursor.…”