A nanocrystal-based PN junction model for quantum dot light-emitting diodes

The PN junction of semiconductors plays an important role in designing and developing light-emitting diodes. In contrast, the characteristics of PN junctions in quantum dot light-emitting diodes (QLED) have been less discussed. In this work, we analyzed the current-voltage (I-V) characteristics of QLED using a modified nano-PN junction model, which combines a silicon-based PN junction model and a hopping transport model. Under the assumption of recombination current dominance in high-efficiency QLEDs, the correlations between complete QLED I-V curves and their constituent sub-device characteristics were derived. The voltage distribution and Quasi-Fermi level splitting of functional layers were performed to elucidate the high ideality factors of QLED devices. The nanocrystal-based PN junction model was extended to simulate the experimental I-V curves of efficient QLED devices. In all, this work not only deepens the device understanding into QLED from the view of semiconductor physics, but also builds up a theoretical framework of nanocrystal-based PN junctions.