Increased Brightness and Reduced Efficiency Droop in Perovskite Quantum Dot Light-Emitting Diodes Using Carbazole-Based Phosphonic Acid Interface Modifiers.
basic_science · Level V
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- Record sourced from PubMed, PMID 39757998.
- Also identified by DOI 10.1021/acsnano.4c13036.
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Abstract
We demonstrate the use of [2-(9<i>H</i>-carbazol-9-yl)ethyl]phosphonic acid (2PACz) and [2-(3,6-di-<i>tert</i>-butyl-9<i>H</i>-carbazol-9-yl)ethyl]phosphonic acid (<i>t</i>-Bu-2PACz) as anode modification layers in metal-halide perovskite quantum dot light-emitting diodes (QLEDs). Compared to conventional QLED structures with PEDOT:PSS (poly(3,4-ethylenedioxythiophene) polystyrenesulfonate)/PVK (poly(9-vinylcarbazole)) hole-transport layers, the QLEDs made with phosphonic acid (PA)-modified indium tin oxide (ITO) anodes show an over seven-fold increase in brightness, achieving a brightness of 373,000 cd m<sup>-2</sup>, one of the highest brightnesses reported to date for colloidal perovskite QLEDs. Importantly, the onset of efficiency roll-off, or efficiency droop, occurs at ∼1000-fold higher current density for QLEDs made with PA-modified anodes compared to control QLEDs made with conventional PEDOT:PSS/PVK hole transport layers, allowing the devices to sustain significantly higher levels of external quantum efficiency at a brightness of >10<sup>5</sup> cd m<sup>-2</sup>. Steady-state and time-resolved photoluminescence measurements indicate that these improvements are due to a combination of multiple factors, including reducing quenching of photoluminescence at the PEDOT:PSS interface and reducing photoluminescence efficiency loss at high levels of current density.