Nanosecond-pulsed electroluminescence from high current–driven quantum-dot light-emitting diodes

Ultrashort optical emission, with pulse duration ranging from nanoseconds to femtoseconds, is usually obtained from lasers. In this work, we achieve nanosecond-pulsed electroluminescence (EL) from a solution-processed fast-response quantum dot light-emitting diode (QLED). By modeling the QLED with a resistor-capacitor equivalent circuit and analyzing the transient current of the circuit, the dynamic of the carrier injection and transport process that fundamentally affects the transient EL of QLED is revealed, which helps to guide the optimization of fast-response QLED. Driven by a high current source, the optimized QLED can output stable and repeatable ultrashort EL with a pulse duration of 20 nanoseconds, a repetition rate of 50 kilohertz, and a high radiant exitance of 5.4 watts per square centimeter. Enabled by the nanosecond-pulsed EL, the developed QLED can be directly used as an instantaneous excitation source for time-resolved fluorescence spectroscopy. Meanwhile, its use as an exposure flash for high-speed imaging is also demonstrated.