Researchers from the Skolkovo Institute of Science and Technology, ITMO University, HSE University and Lund University have demonstrated a perovskite laser diode that lases under a steady direct current, without relying on epitaxial growth - a long-sought result that has repeatedly eluded the field.
Halide perovskites have been an attractive candidate for electrically driven microlasers for years, mainly because of how well they perform under optical excitation. Single-crystal cavities and solution-assembled microstructures made from these materials have repeatedly delivered low lasing thresholds when pumped with light. Getting the same devices to lase from direct electrical injection - with electrons and holes fed straight into the perovskite - has proven far harder, and a true, directly electrically pumped perovskite laser diode had not been demonstrated.
Researchers have previously approached the problem indirectly. One strategy paired a high-luminosity LED with a separate high-gain medium inside a dual-cavity architecture, using the LED as an optical pump rather than injecting carriers into the lasing medium itself. Another used a perovskite LED excited by short optical pulses, where electrically injected carriers produced amplified spontaneous emission (ASE) - a precursor to lasing, but not lasing itself. Further engineering of perovskite LED architectures pushed carrier densities higher still, yet full electrical lasing remained out of reach.
The new device tackles the core bottleneck directly: injecting balanced, high-density carriers into a perovskite microcavity without damaging the material or disrupting its electronic structure. Rather than growing the diode epitaxially, the team built it from a solution-grown CsPbBr3 microplate contacted with chemically inert single-walled carbon nanotube (SWCNT) electrodes, then embedded the assembly inside an optical microcavity.
Cooling the device to 8 K while holding the current constant causes a perovskite p-i-n diode to form within the microplate-electrode assembly. That self-formed diode structure is what allows balanced carrier injection at high current densities - a step the researchers describe as crucial, since unbalanced injection normally wastes carriers or diverts them into nonradiative decay pathways that block coherent emission.
With injection solved, the researchers used the optical cavity to push the system into the strong coupling regime, where light and matter hybridize into polaritons - quasiparticles that can lase once gain exceeds losses. Driving the integrated microcavity diode this way produced polariton lasing rather than conventional weak-coupling emission. The threshold for this behavior was strikingly low: polariton lasing appeared under a direct current of just 65 μA.
Such a low operating current for an electrically pumped, non-epitaxial perovskite device points toward a practical, chip-compatible route to coherent perovskite light sources - shifting perovskite photonics from a purely optical curiosity toward something that can be driven electrically like a real device. The approach the team highlights - engineering carrier injection through non-traditional contacts, then letting strong coupling handle the coherent emission - may offer a template for further work in the field.
