Unveiling the Carrier Dynamics of Perovskite Light-Emitting Diodes via Transient Electroluminescence.

Perovskite light-emitting diodes (PeLEDs) have garnered significant attention due to their outstanding optoelectronic properties. However, investigating carrier transport and recombination behavior during device operation poses persistent challenges. In this study, we explore the impact of additive and interface engineering on device performance using transient electroluminescence (TREL). Polyethylene glycol (PEG) induces the formation of square-faceted nanocrystals with a homogeneous size distribution and extended fluorescence lifetime. Consequently, these PeLEDs exhibit remarkable stability. Additionally, employing an electron transport layer of 2,4,6-tris[3-(diphenylphosphino)phenyl]-1,3,5-triazine (PO-T2T), which has a better match to the energy bands of the perovskite layer and a higher carrier mobility, allows for lower turn-on voltage and faster response but also suffers from a short decay time and poor stability. Moreover, low-temperature TREL characterization shows that the carrier mobility is also significantly suppressed with decreasing temperature, which reduces the transient response speed.