The perovskite structure was first identified in 1839 when the mineral calcium titanate (CaTiO₃) was discovered and named after the Russian mineralogist L.A. Perovski. The term "perovskite" now broadly refers to materials that share the same crystal structure as CaTiO₃, particularly those used in optoelectronics, which typically have the chemical formula ABX₃ (where A cation can be Cs⁺, CH₃NH₃⁺, and HC(NH₂)₂⁺, B is usually a metal ion (e.g., Pb²⁺ and Sn²⁺), and X is halide anion (e.g., I⁻, Br⁻, and Cl⁻))^[1]. Perovskite materials are classified into different categories according to their dimensionality, as illustrated in Fig. 1. These include three-dimensional (3D) perovskites, two-dimensional (2D) perovskites, quasi-two-dimensional (quasi-2D) perovskites, one-dimensional (1D) perovskites, and zero-dimensional (0D) perovskites^{[2, 3]}. 3D perovskites have attractive features like strong and panchromatic absorption, direct photogeneration of free carriers, efficient charge transport, and long carrier diffusion lengths^[4], making them suitable for fabricating high efficiency solar cells. 2D perovskites exhibit several distinct properties, including multiple quantum well structures and high exciton binding energies^[5]. Besides, 2D perovskites show superior stability compared to their 3D counterparts. This can be ascribed to several factors, including better moisture resistance of hydrophobic organic cations, a larger energy barrier to ion migration, and an increased tolerance to structural stress^[6]. Quasi-2D perovskites are distinctive due to their intrinsic quantum-well structures, resulting in a high exciton binding energy. Their mixed-phase composition enables efficient photocarrier transfer from higher to lower bandgap species, thereby enhancing carrier density and passivating defect states. This, in turn, improves radiative recombination efficiency and photoluminescence quantum yields (PLQYs). Additionally, these perovskites provide the additional benefit of tunable spectra through composition and dimensionality engineering, which enables continuously tunable photoluminescence emission^{[7, 8]}. 1D nanostructured perovskites are extensively used in various photonic and optoelectronic devices. Their remarkable properties include long diffusion lengths, charge carrier lifetime and charge confinement effect resulting from their specific geometries^[9]. Solution-processable 0D perovskites provide the potential for tunable emission and enhanced moisture, oxygen, and photostability. They can be applied to LEDs and lasers due to their high quantum efficiency. Nevertheless, a number of challenges remain for 0D perovskites, including the development of effective methods for controlling the size and reducing the number of surface defects. Addressing these challenges is vital for commercializing 0D perovskites and unlocking their full potential in practical applications^[10].

In view of the promising optoelectronic properties and adjustable dimensionality of perovskites, they have attracted great attention for the application in various optoelectronic devices. It has been well demonstrated that halide perovskite material has diverse applications in various fields, including solar cells, light-emitting diodes (LEDs), photodetectors, lasers, memristors, artificial synapses devices, pressure-induced emission, and so on, as shown in Fig. 2^[12]. Here, we will focus on the advances in perovskite-based lasers. Furthermore, prospective on future research directions and challenges in the practical technology applications of perovskite lasers will be provided, offering insights into the evolving landscape of this emerging field.

Laser refers to light amplification by stimulated emission of radiation^[13], which can generate pure and intense light. It comprises three key elements: gain medium, optical feedback resonator, and pumping source. Metal halide perovskite materials are highly suitable for use as gain media in laser applications due to their exceptional optical properties^[14].

The research field of semiconductor lasers lies at the heart of semiconductor photonics, bridging fundamental science with a wide array of vital technologies. Semiconductor lasers are among the most widely used and significant types due to their long lifespan, compact size, low electrical power requirements, and compatibility with mature semiconductor technology^[15]. Critical challenges in semiconductor laser research include device miniaturization and energy efficiency, wavelength diversity, and system integration^[16].

The latest advances in nanoscience and nanotechnology have resulted in the reduction of the size of semiconductor lasers to below 100 nm, thereby establishing semiconductor micro/nanolasers as a key area of research for the development of high-speed, low-energy display and communication devices^{[17, 18]}. However, conventional semiconductor lasers, based on materials like GaN, InP, and GaAs, are typically produced via high-cost, energy-intensive methods including metal−organic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE)^[19]. On the contrary, solution-processed lasers offer the potential for cost reduction and the possibility of printable and flexible applications. Despite the exploration of organic semiconductor lasers over the past two decades to meet these needs, their inadequate electrical properties and undesirable crystal disorder have limited their effectiveness in current devices^[20]. As a result, achieving electrically driven, solution-processed lasers remains a significant challenge in the field of laser research. Recently, metal halide perovskites have emerged as promising candidates due to their exceptional optoelectronic properties, including high emission efficiency, broad color emission, and the ability to be synthesized via low-temperature solution processes^{[21, 22]}. These unique properties of perovskite materials have facilitated the development of numerous high-performance laser applications (Fig. 3), including edge-emitting amplified spontaneous emission (ASE)^[23], vertical cavity surface emitting lasers (VCSELs)^{[24, 25]}, distributed feedback (DFB) lasers^[26], microlasers^[27], plasmonic nanolasers^[28], polariton lasers^[29], bound in continuum state (BIC) lasers^[30], hybrid plasmonic surface lattice resonance lasers^[31] and microring lasers coupled to long-range surface plasmon polariton waveguide^[32].

Over the past decade, there has been rapid progress in metal halide perovskite lasers, with numerous studies focusing on materials engineering to enhance their performance. Tremendous advancements have been achieved in enhancing the performance, expanding the capabilities, and broadening the applications of perovskite lasers through the establishment of a resonator (optical cavity), designing the composition of metal halide perovskites, applicating in flexible devices, setting controllable fabrication and processing methods, using effective protection layers, changing the device architecture, managing charge conduction.

To achieve lasing, establishing a coherent optical field within a resonator is crucial for the use of optical positive feedback. This determines the resonant lasing modes within the gain spectrum and the spatial properties of the output beam^[33]. Chiral microlasers offer considerable promise for the advancement of optoelectronics, with applications spanning from integrated photonic devices to high-density quantum information processing^{[34, 35]}. While significant progress has been made in the field of lead-halide perovskite emitters, achieving chiral lasing with high dissymmetry factors (g_lum) has remained a challenge. Recently, researchers unveiled an innovative method to develop chiral single-mode microlasers offering outstanding stability and tunable emission. This is accomplished by combining CsPbCl_xBr_3−x perovskite microrods (MRs) with a cholesteric liquid crystal (CLC) layer (Fig. 4(a))^[34]. The perovskite MRs, featuring a whispering gallery mode (WGM) microcavity, exhibit lasing with an exceptional Q-factor of 3017 (Fig. 4(b)) and a low lasing threshold of 81.8 μJ∙cm^–2 (Fig. 4(c)). The CLC layers, acting as chiral elements, convert the linearly polarized lasing from the MRs into circularly polarized lasing (CPL) through Bragg reflection. This process generates CPL with a g_lum reaching as high as 1.62 (Fig. 4(d)). This study presents a significant breakthrough in the field of perovskite chiral microlasers by successfully demonstrating wavelength-tunable single-mode CPL with high g_lum and exceptional stability. Crucially, the lasing wavelength of the microlaser is tunable across a wide range of visible wavelengths from deep blue to pure green, achieved by controlling the halide composition of the perovskite MRs and adjusting the photonic bandgap of the CLCs.

The laser wavelength of perovskite can be easily adjusted by altering its material composition. Mixing halide anions is the most effective strategy for tailoring the output wavelength of perovskite lasers. The researchers illustrate the capability of wavelength tuning from 420 to 530 nm through the utilization of CsPbCl_xBr_3–x MRs with varying Cl/Br ratios (Fig. 4(e)). Additionally, a deep blue chiral microlaser exhibiting a g_lum of approximately 1.6 has been realized using CsPbCl₃ in conjunction with chiral liquid crystals (CLCs) that possess a corresponding photonic bandgap^[34]. These microlasers also demonstrate remarkable stability, maintaining constant laser output under continuous pumping for over 1.8 × 10⁶ lasing shots within a 30-min timeframe (Fig. 4(g)) and sustaining a g_lum of about 1.6 after a month of storage in ambient conditions (Fig. 4(h)). The exceptional stability is attributed to the protective CLC layer and substrate, which effectively shield the perovskite MRs from moisture and oxygen. The exceptional properties of chiral microlasers make them highly promising components for the advancement of next-generation on-chip computing, information processing, nanophotonics, and diagnostic applications.^{[34, 36, 37]}.

The progress of perovskite lasers facilitates the development of low-threshold, external-cavity-free devices that operate at ambient temperature (Fig. 5(a)−5(c)). Perovskite lasers based on MAPbBr₃, processed in solution at low temperatures, have exhibited a peak emission wavelength of approximately 550 nm and a linewidth of approximately 0.3 nm, yielding a quality factor of around 1900. The achieved low lasing thresholds are measured at 9.3 µJ∙cm⁻² for lasers mounted on rigid substrates and 14.6 µJ∙cm⁻² for those on flexible substrates^[38]. These values are comparable to those reported for high-performance perovskite microlasers that employ meticulously designed external resonators^[30]. We are expected to observe several experimental phenomena for laser devices, such as emission polarization, narrowed linewidth, lasing onset, etc. They demonstrate stable operation with a half-life of over 1.8 × 10⁸ pulses under optical pumping at 20 µJ∙cm⁻² in air at room temperature. Investigations utilizing transient absorption and emission techniques indicate that the low lasing thresholds can be attributed to an enhanced band-to-band spontaneous emission process and minimized Auger recombination losses in high-quality microcrystalline MAPbBr₃ perovskite. Furthermore, the flexible perovskite lasers demonstrated remarkable mechanical durability which is comparable to the most advanced flexible lasers derived from organic and perovskite semiconductor materials^{[39, 40]}. The simplicity of the spin-coating process, along with the absence of external cavities, offers the potential for high-throughput, all-solution fabrication of perovskite lasers. This could facilitate their low-cost integration with next-generation flexible and non-planar devices, with prospective applications in wearable electronics, healthcare, and robotics^[38].

A range of controllable fabrication and processing techniques have been developed to obtain perovskite lasers. A scalable bottom-up method is proposed to create self-assembled CsPbBr₃ perovskite microwires, or waveguides, capable of operating in the strong coupling regime, enabling polariton condensation and edge lasing^[41] (Fig. 5(d) and 5(e)). These microwires can be formed in various geometries utilizing a microfluidic technique that optimizes nucleation and crystal growth. The resulting CsPbBr₃ microwires maintain excellent optical quality and are capable of bending without damage. Furthermore, they can be fabricated on any substrate without requiring a flat surface or complex chemistry. This approach is more compatible with silicon-based photonic devices and simplifies the integration of on-chip polaritonic devices, making them more cost-effective than traditional devices. Lateral edge and corner-mode polariton lasing are demonstrated in these microwires, initiated by non-resonant excitation of exciton-polaritons. Angle-resolved spectroscopy shows evidence of strong mutual coherence between distinct lasing edges, revealing sharp interference patterns in reciprocal space. The ability to guide polariton propagation over long distances positions these microwires as promising candidates for future room-temperature polaritonic integrated circuits, leveraging the unique properties of CsPbBr₃ perovskite. This work paves the way for the integration of perovskite materials into photonic devices, with the potential to advance the development of novel laser systems.

The development of continuous-wave (CW) lasers has been a significant area of research within the field of optoelectronic integrated circuits^[42]. The emergence of CW pumped perovskite lasers has catalyzed efforts to develop electrically driven perovskite lasers for commercialization. Metal halide perovskites are promising materials for thin-film laser diodes. The phenomenon of stimulated emission occurs when the excitation density reaches a threshold at which the optical gain exceeds the propagation loss, resulting in the formation of a stimulated emission band within the spectral region characterized by the highest gain. This typically occurs owing to the amplification of spontaneous emission, which is why it is referred to as amplified spontaneous emission (ASE). Elevated levels of ASE and laser thresholds under pumping conditions necessitate enhanced photostability and thermal stability of optical gain materials, a requirement that is particularly stringent for lead halide perovskites. Consequently, it is advantageous to reduce the ASE and laser thresholds of perovskite materials to achieve stable and sustained laser light^[43]. However, the realization of electrically excited ASE in perovskite light-emitting diodes (PeLEDs) has been challenging due to the dual requirement for both high conductivity and high net modal gain. By changing the device structures, the ASE threshold can be effectively reduced. Elkhouly et al. presented a vertical transparent PeLED design (Fig. 5(f) and 5(g)) that minimized free carrier absorption losses while enhancing current injection. At 77 K, ASE was achieved with a 9.1 μJ∙cm⁻² threshold using 2.3 ns optical pulses. By applying sub-microsecond electrical excitation, current densities exceeding 3 kA∙cm⁻² and irradiance above 40 W∙cm⁻² were achieved (Fig. 5(h)). Notably, synchronizing optical pulse co-pumping with electrical pulses reduced the ASE threshold by 1.2 ± 0.2 μJ∙cm⁻², demonstrating that electrically injected carriers enhance optical gain. The testing of the PeLED with a 1-μs-long optical excitation revealed continuous-wave ASE at a threshold of 3.8 kW∙cm⁻². Furthermore, intense electrical pulses generated nearly half of the electroluminescence brightness that was observed with continuous wave optical pumping at the ASE threshold. This research suggests that the development of perovskite semiconductor optical amplifiers and injection lasers is feasible utilizing this transparent PeLED architecture^[44].

The precise regulation of conductivity and its polarity is crucial in the field of modern electronics. For halide perovskites, effective strategies for controlling charge conduction while preserving superior optoelectronic properties are still being developed. Xiong et al. show that p- and n-type behaviors in wide-bandgap mixed-cation lead bromide perovskite samples can be controlled using the (4-(9H-carbazol-9-yl)butyl) phosphonic acid (4PACz). The resulting carrier concentrations exceeded 10¹³ cm⁻³ for both p-type and n-type samples, with Hall coefficients ranging from −0.5 m³∙C⁻¹ (n-type) to 0.6 m³∙C⁻¹ (p-type). The transition from n-type to p-type conductivity was accomplished while maintaining photoluminescence quantum yields between 70% and 85%. This doping enabled ultrahigh brightness (1.16 × 10⁶ cd∙m⁻²) and an external quantum efficiency (EQE) of 28.4% in hole transport layer-free perovskite light-emitting diodes with a sample^[45]. These advanced devices present considerable advantages over other solution-processed light-emitting diodes and are poised to initiate a new era of optoelectronic devices, including efficient perovskite lasers.

It is anticipated that perovskite will play a pivotal role in developing next-generation optoelectronic devices. Their unique and tunable optoelectronic properties make them highly versatile for applications across a broad spectrum, including solar cells, light-emitting diodes, lasers, and beyond. As research progresses, there is a growing focus on optimizing perovskite materials for specific applications, particularly in laser technology, where they offer a potential pathway to low-threshold or even thresholdless lasing. These indicate a strong push towards the development of more efficient and stable perovskite-based lasers, with a particular focus on controlling material properties and exploring new device architectures. The progress in this field is promising for the future of optoelectronics and photonics. Moreover, perovskite materials can be employed as high-performance lasers, which can be deployed in the fabrication of solar cells. For instance, laser patterning can be utilized for the upscaling of perovskite solar cells, while ultrafast laser annealing can be applied to perovskite films. It has been demonstrated that the utilization of perovskites in optoelectronics may facilitate mutual advancement, with research on perovskites potentially fostering collaborative development across multiple disciplines. Continued research and development efforts focusing on optimizing material properties, device architectures, and manufacturing processes are essential to fully realizing the potential of perovskite materials in optoelectronic applications. Enhancing ASE can focus on realizing higher gain length, lower density of states, and smaller optical loss. To achieve electrically pumped metal halide perovskite lasers, three key goals should be simultaneously satisfied: continuous wave lasing, the ability to inject a high density of charge carriers, and the integration of the optical cavity with LED structure. Addressing these key issues will require an interdisciplinary approach, combining materials science, device engineering, artificial intelligence, and other subjects related to photonics. For example, machine learning methods like neural networks can be leveraged in the simulation to predict optimal perovskite compositions and device architectures for lasing. It is hoped that in the future, the stability problem of perovskites can be solved to develop fully electrically pumped perovskite lasers, as well as commercial perovskite lasers that can be used to assist the manufacture of perovskite solar cells.