| Popis: |
Metal halide perovskite materials have emerged as a unique class of solution process compatible semiconductors and alluring candidates for high-performance optoelectronic applications1,2,3, especially light-emitting diodes (LEDs), owing to high quantum efficiency, facile color tunability, narrow emission line widths, as well as cost-effectiveness4,5,6. Despite of the great successes on green and red perovskite LEDs (PeLEDs), the advancement of external quantum efficiency (EQE) of blue PeLEDs still lags far behind those of green and red PeLEDs7,8. Here, we demonstrate color-tunable blue PeLEDs devices with high EQE of 16.1% and 10% for emission wavelengths of 472 nm and 461 nm, respectively. The efficient tunable wavelength electroluminescence (EL) and high (EQE) originate from the optimization of the recombination zone position to reach the charge injection balance in the vertically graded bandgap quasi-2D perovskite materials. Under the synergetic effect of lead chloride (PbCl2) doping and propane-1,3-diammonium (PDABr2) incorporation, the vertically graded bandgap perovskite materials can be prepared by the self-regulation of the reduced-dimensional perovskite during the annealing process. Our work here has significantly elevated the performance of the current blue PeLEDs. It opens up a novel avenue to fabricate high-performance blue PeLEDs that can match up the performance of the green and red PeLEDs for future lighting and display applications. |
