Nanosecond‐Pulsed Perovskite Light‐Emitting Diodes at High Current Density

Abstract

be grown epitaxially on specific substrates, silicon not being one of them.Metal halide perovskite light-emitting diodes (PeLEDs) hold the potential for a new generation of display and lighting technology, [1][2][3][4][5][6][7] featuring high color quality, energy efficiency, and low manufacturing cost. Furthermore, perovskites can be deposited from solutions/inks, which means that they can be deposited on virtually any substrate including silicon. Perovskite LEDs have been shown to be promising for optical communications. [8] However, the operation speed of PeLEDs is still relatively slow, with electroluminescence (EL) rise times of several hundred nanoseconds or longer. [9][10][11][12] The slow operation speed and response time of PeLEDs limit their potential for a wider scope of applications, such as interchip and intrachip optical communications, currently realized with more expensive technologies using III-V semiconductors.Reducing the EL rise time of PeLEDs will not only increase their potential utility for applications in optical communications, but also contribute to the development of an electrically driven perovskite laser diode, which would be transformative in the optoelectronics realm as a low-cost laser source compatible with silicon microelectronics. Despite significant progress toward this goal, [13][14][15][16] electrically driven lasing in perovskites has not yet been achieved. One challenge is that the current density reported to date does not exceed the estimated threshold required for lasing. Reducing the EL rise time would enable shorter pulse operation, making it possible for PeLEDs to operate at higher current densities due to reduced Joule heating. [10,17] Furthermore, high-speed pulsed operation of PeLEDs will allow us to probe electrically stimulated chargecarrier dynamics and reveal mechanisms that prevent PeLEDs from operating efficiently or lasing under electrical excitation. This understanding is particularly important as optically pumped lasing death has been observed for perovskite thin films within 25 ns, [18] and optical and electrical excitations are considerably distinct.Both extrinsic factors (e.g., parasitic capacitance and resistance) and intrinsic factors (e.g., long recombination lifetime of charge carriers in the light-generating process) can limit the speed of PeLEDs. However, the speed of PeLEDs reported so far appears to have been dominantly constrained by extrinsic factors, [8][9][10][11][12] excluding the possibility to probe more intrinsic While metal-halide perovskite light-emitting diodes (PeLEDs) hold the potential for a new generation of display and lighting technology, their slow operation speed and response time limit their application scope. Here, high-speed PeLEDs driven by nanosecond electrical pulses with a rise time of 1.2 ns are reported with a maximum radiance of approximately 480 kW sr −1 m −2 at 8.3 kA cm −2 , and an external quantum efficiency (EQE) of 1% at approximately 10 kA cm −2 , through improved device configuration designs and material consi...

Ion Migration in Perovskite Light‐Emitting Diodes: Mechanism, Characterizations, and Material and Device Engineering

“…Shrinking the emission area and driving device in a pulse mode can effectively reduce Joule heating and achieve high injection current at kA cm −2 level without causing excessive deterioration in the device. [152,155,259] Kumawat et al investigated ion migration under pulse-mode operation with the pulse frequencies ranging from 10 Hz to 20 kHz and found the current transient at low frequencies (10-200 Hz) is associated with movement of mobile ions. [260] In contrast, at higher frequencies, the mobile ions cannot respond to the change of the electric field and accordingly the device lifetime increased with the increasing pulse frequency.…”

Metal Halide Perovskites toward Electrically Pumped Lasers

“…Furthermore, Zhao et al showed a 150 × 200 μm 2 LED obtained from the similar crossover of Ag strip and ITO (Figure 15f). [73] The pulse width was narrower (30 ns) and the duty cycle was reduced by an order of magnitude. After improving the material properties and device configuration, they ultimately achieved an EQE of 1% at 10 kA cm −2 (Figure 15f).…”

“…[4,258] Therefore, the selection of transport layers with comparable mobility, strong blocking to opposite carriers and small barriers with perovskites is crucial to guarantee balanced charge transport. [73,254] Furthermore, optimization of the energy level alignment by doping in the transport layers or inserting an interfacial layer can also improve the charge balance and further suppress Auger recombination. [259,260] Excitons in perovskites may be dissociated into electrons and holes and migrate to opposite heterogeneous interfaces under electric field, which is detrimental to population inversion.…”

Intense Electrical Pulsing of Perovskite Light Emitting Diodes under Cryogenic Conditions

“…Encouragingly, several important achievements toward this goal have been reported, in particular optically‐pumped continuous‐wave ASE/lasing in perovskite films at both cryogenic and room temperatures (RT), [ 8–10 ] optically‐pumped ASE from a complete perovskite light emitting diode (PeLED) stack, [ 11,12 ] and intense electrical excitation of PeLEDs up to several kA cm −2 current density. [ 13–16 ]…”

“…perovskite light emitting diode (PeLED) stack, [11,12] and intense electrical excitation of PeLEDs up to several kA cm −2 current density. [13][14][15][16] Previous studies have shown that Joule heating is a detrimental factor that lowers the device performance at high current injection, even for small-scale PeLEDs excited with sub-microsecond electrical pulses. [13,14,16] Therefore, the reduction of the device operating temperature has been considered as one of the key strategies that likely must be applied in order to achieve electrically pumped perovskite lasing.…”