In a recent review article published in the journal Advanced Photonics, researchers summarized recent advancements in utilizing transient electroluminescence (TrEL) measurements to study carrier dynamics, efficiency roll-off, and ion migration in perovskite light-emitting diodes (LEDs), aiming to advance the understanding of their operational mechanisms.
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Transient electroluminescence (TrEL) is increasingly being used to probe carrier dynamics, efficiency roll-off, and ion migration in perovskite light-emitting diodes (PeLEDs), according to a recent review in Advanced Photonics.
In the review, the authors describe TrEL as a practical way to track time-dependent electronic processes in operating LEDs using pulsed voltage excitation. By recording time-resolved electroluminescence during and after a voltage pulse, researchers can separate processes that occur on very different time scales, including nanosecond carrier recombination and millisecond ion migration.
A key benefit is that low-duty-cycle pulsing can reduce device heating compared with direct current operation. This makes it possible to study ultrahigh current density regimes that can be difficult to access under steady-state bias, which is relevant for investigating efficiency roll-off and potential Auger recombination effects. The review also notes that TrEL can be combined with external fields (for example, magnetic fields) to explore spin-dependent transport and magneto-optic effects in PeLEDs.
Studies highlighted in the review
The authors group recent TrEL work into three main areas: carrier dynamics, efficiency roll-off at ultrahigh current densities, and ion migration.
For carrier dynamics, TrEL has been used to examine injection, transport, and recombination in full device stacks. The turn-on delay can reflect carrier transit and exciton formation and has been used to estimate mobility. Features such as plateaus, decay under high current, and overshoot behavior have been linked to recombination balance, quenching pathways, and interfacial injection or blocking behavior. Microsecond-scale decay on the falling edge has also been analyzed to separate slow de-trapping contributions from recombination, supporting low trap density estimates in some devices.
For efficiency roll-off, TrEL studies cited in the review point to Joule heating, injection imbalance, and carrier leakage as major contributors. Pulsed TrEL experiments have shown reduced electroluminescence degradation with improved thermal management (for example, sapphire substrates or graphite heat spreaders). Lower duty cycles can further reduce roll-off, consistent with a role for injection imbalance. In some reports, emission from transport layers has been used as evidence of carrier leakage. The review also discusses transient photoluminescence-on-TrEL approaches that have been used to argue Auger recombination is negligible in certain cases.
For ion migration, TrEL can track millisecond-scale intensity increases attributed to electric-field redistribution by mobile ions. These transients show strong dependence on temperature and bias history, indicating that ion configurations can affect device behavior and stability during operation.
Limitations and outlook
The review notes that TrEL is typically limited in temporal resolution compared with optical photophysics methods such as transient photoluminescence (T-PL) and transient absorption (TA). RC delays, along with the finite time required for electrical injection, can make TrEL less suitable for ultrafast processes such as electron–phonon coupling. Because TrEL excites the full multilayer stack, separating layer-specific or interface-specific contributions can also be challenging, particularly when field distributions are non-uniform. The authors caution that slow tails dominated by de-trapping can complicate extraction of true recombination rates.
Even with these constraints, the review describes ongoing expansion of TrEL through multimodal measurements (including optical and thermal stimuli) and its use in other perovskite device concepts, such as light-emitting perovskite field-effect transistors. The technique is also discussed in the context of evaluating pixel-level stability for display applications and supporting development of electrically pumped perovskite laser diodes, where pulsed excitation can help manage heating at very high current densities.