Enhancing the efficiency of green perovskite-QDs-based light-emitting devices by controlling interfacial defects with diamine molecules

Inorganic perovskite quantum dots (QDs) have emerged as promising materials for light-emitting devices by merits of their high photoluminescence quantum yield (PLQY), narrow full width at half-maximum and tunable emission spectrum. However, fluorescence quenching and trap-mediated nonradiative recombination between hole transport layer (HTL) and QD films are prejudicial to the performance of perovskite-QDs-based lightemitting devices (QLEDs). Here, HTL was modified with diamine molecules (1,4-butanediamine (4-DA), 1,8-octyldiamine (8-DA) and 1,11-aminoundecylamine (11-DA)) through a simple self-assembly method. QD films based on modified poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)-benzidine] (Poly-TPD) exhibited higher PL intensity and lower fluorescence quenching properties. Meanwhile, diamine molecules do favor to the flatness of Poly-TPD film and contribute to the smoothness of QD films. Moreover, the exciton quenching and the density of defects at the interface between HTL and QD films were effectively reduced. Particularly, QLEDs based on HTL modified with 8-DA was endowed with a maximum luminance of 78634 cd/m(2), a peak current efficiency of 30.77 cd/A, a maximum external quantum efficiency of 8.90% and T-50 of 16.8 min when the initial brightness is about 1000 cd/m(2).

Automated summary

The study investigated the effects of modifying HTL with different diamine molecules through a simple self-assembly method, finding that this modification can increase the fluorescence intensity of perovskite quantum dot films, reduce fluorescence quenching, and contribute to film flatness and smoothness. It also effectively reduces the defect density and exciton quenching at the interface between HTL and QD films.