Solvent Recrystallization-Enabled Green Amplified Spontaneous Emissions with an Ultra-Low Threshold from Pinhole-Free Perovskite Films

Green and amplified spontaneous emissions with low thresholds are crucial for the development of solution-processable perovskite light sources. Although mixed-cation CsPbBr₃ perovskites are highly promising, pinholes are inevitably formed during the spin-coating process, which results in considerable optical losses. This study proposes a solvent recrystallization strategy to reduce the number of pinholes and enhance the crystallinity of (Cs, FA, MA)PbBr₃/NMA (FA = CH(NH₂)₂, MA = CH₃NH₃, and NMA = C₁₁H₉NH₃) films in a dimethyl sulfoxide gas environment. Amplified spontaneous green emissions are produced with a low threshold of 1.44 μJ cm⁻² and a high net modal gain of 1176 cm⁻¹. The reduced threshold is attributed to the relatively low propagation loss and suppressed Auger recombination, which results from the formation of a pinhole-free surface and enlarged grain size. These results can be utilized in the development of high-performance perovskite laser devices.     

Exciton Dynamics and Optically Pumped Lasing in 1-Naphthylmethylamine-Based Quasi-2D Perovskite Films

Films of the quasi-2D perovskite based on 1-naphthylmethylamine (NMA) are promising as the gain medium for optically pumped lasing and future electrically pumped lasing because of its low lasing threshold and small electroluminescence efficiency rolloff. However, reasons for the low threshold and small efficiency rolloff are still unclear. Therefore, exciton dynamics are investigated in NMA-based quasi-2D perovskite films. It is found that quenching of bright excitons by other excitons or charge carriers is unlikely in NMA-based quasi-2D perovskite films, which is one reason for the low lasing threshold and small efficiency rolloff. Moreover, thermally stimulated current measurements reveal that the defect levels inside the band gap of the NMA-based quasi-2D perovskite are shallow, with a depth of ≈0.3 eV, causing a decrease in nonradiative exciton recombination through the defects. Therefore, population inversion can be easily achieved, leading to the low lasing threshold as well. For fabrication of NMA-based quasi-2D perovskite laser devices with even lower lasing thresholds, a circular-shaped optical resonator, and small-molecule-based defect passivation are used. Optically pumped lasing can be obtained from these devices, with a threshold of ≈1 µJ cm⁻², which is one of the lowest values ever reported in any perovskite lasers.     

High-Performance Photodetector and Angular-Dependent Random Lasing from Long-Chain Organic Diammonium Sandwiched 2D Hybrid Perovskite Non-Linear Optical Single Crystal

3D organic-inorganic metal halide perovskites are excellent materials for optoelectronic applications due to their exceptional properties, solution processability, and cost-effectiveness. However, the lack of environmental stability highly restricts them from practical applications. Herein, a stable centimeter-long 2D hybrid perovskite (N-MPDA)[PbBr₄] single crystal using divalent N1-methylpropane-1,3-diammonium (N-MPDA) cation as an organic spacer, is reported. The as-grown single crystal exhibits stable optoelectronic performance, low threshold random lasing, and multi-photon luminescence/multi-harmonic generation. A photoconductive device fabricated using (N-MPDA)[PbBr₄] single crystal exhibits an excellent photoresponsivity (≈124 AW⁻¹ at 405 nm) that is ≈4 orders of magnitudes higher than that of monovalent organic spacer-assisted 2D perovskites, such as (BA)₂PbBr₄ and (PEA)₂PbBr₄, and large specific detectivity (≈10¹² Jones). As an optical gain media, the (N-MPDA)[PbBr₄] single crystal exhibits a low threshold random lasing (≈6.5 µJ cm⁻²) with angular dependent narrow linewidth (≈0.1 nm) and high-quality factor (Q ≈ 2673). Based on these results, the outstanding optoelectronic merits of (N-MPDA)[PbBr₄] single crystal will offer a high-performance device and act as a dynamic material to construct stable future electronics and optoelectronic-based applications.     

2D Antiferroelectric Hybrid Perovskite with a Large Breakdown Electric Field And Energy Storage Density

Energy conversion and storage devices are highly desirable for the sustainable development of human society. Hybrid organic–inorganic perovskites have shown great potential in energy conversion devices including solar cells and photodetectors. However, its potential in energy storage has seldom been explored. Here the crystal structure and electrical properties of the 2D hybrid perovskite (benzylammonium)₂PbBr₄ (PVK-Br) are investigated, and the consecutive ferroelectric-I (FE1) to ferroelectric-II (FE2) then to antiferroelectric (AFE) transitions that are driven by the orderly alignment of benzylamine and the distortion of [PbBr₆] octahedra are found. Furthermore, accompanied by field-induced AFE to FE transition near room temperature, a large energy storage density of ≈1.7 J cm⁻³ and a wide working temperature span of ≈70 K are obtained; both of which are among the best in hybrid AFEs. This good energy storage performance is attributed to the large polarization of ≈7.6 µC cm⁻² and the high maximum electric field of over 1000 kV cm⁻¹, which, as revealed by theoretical calculations, originate from the cooperative coupling between the [PbBr₆] octahedral framework and the benzylamine molecules. The research clarifies the discrepancy in the phase transition character of PVK-Br and shed light on developing high-performance energy storage devices based on 2D hybrid perovskite.     

High Q-Factor and Low Threshold Continuous-Wave Near-Infrared Lasing with Quasi-2D Perovskites

Quasi-2D perovskites have shown great potential in achieving solution-processed electrically pumped laser diodes due to their multiple-quantum-well structure, which induces a carrier cascade process that can significantly enhance population inversion. However, continuous-wave (CW) optically pumped lasing has yet to be achieved with near-infrared (NIR) quasi-2D perovskites due to the challenges in obtaining high-quality quasi-2D films with suitable phase distribution and morphology. This study regulates the crystallization of a NIR quasi-2D perovskite ((NMA)₂FA_n−1Pb_nI_3n+1) using an 18-crown-6 additive, resulting in a compact and smooth film with a largely improved carrier cascade efficiency. The amplified spontaneous emission threshold of the film is reduced from 47.2 to 35.9 µJ cm⁻². Furthermore, by combining the film with a high-quality distributed feedback grating, this study successfully realizes a CW NIR laser of 809 nm at 110 K, with a high Q-factor of 4794 and a low threshold of 911.6 W cm⁻². These findings provide an important foundation for achieving electrically pumped laser diodes based on the unique quasi-2D perovskites.     

Light Emitting Diodes Based on Inorganic Composite Halide Perovskites

CsPbBr₃ is a promising type of light‐emitting halide perovskite with inorganic composition and desirable thermal stability. The luminescence efficiency of pristine CsPbBr₃ thin films, however, appears to be limited. In this work, light emitting diodes based on CsPbBr₃|Cs₄PbBr₆ composites are demonstrated. Both quantum efficiency and emission brightness are improved significantly compared with similar devices constructed using pure CsPbBr₃. The high brightness can be attributed to the enhanced radiative recombination from CsPbBr₃ crystallites confined in the Cs₄PbBr₆ host matrix. The unfavorable charge transport property of Cs₄PbBr₆ can be circumvented by optimizing the ratio between the host and the guest components and the total thickness of the composite thin films. The inorganic composition of the emitting layer also leads to improved device stability under the condition of continuous operation.     

Pyrene‐Capped Conjugated Amorphous Starbursts: Synthesis,Characterization, and Stable Lasing Properties in Ambient Atmosphere

A family of trigonal starburst conjugated molecules (TrFPy, TrFPy, and TrF2Py) composed of a truxene core and pyrene cappers with various bridge lengths is synthesized and characterized. The incorporation of pyrene cappers successfully depress the crystallization tendency, resulting in enhanced glassy temperature and improved morphological stability of the thin films. The high photoluminescence yield in neat films and excellent thermal stability render these pyrene‐capped starbursts promising lasing optical gain media. Low amplified spontaneous emission (ASE) thresholds (E_th^ASE) of 180 nJ pulse^‐1 and 101 nJ pulse^–1 were recorded for TrFPy and TrF2Py, respectively. One dimensional distributed feedback (1D DFB) lasers demonstrated lasing threshold of 9.3 kW/cm² and 7.3 kW/cm² for TrFPy (at 457 nm) and TrF2Py lasers (at 451 nm), respectively. The ASE performance of TrFPy and TrF2Py in an ambient condition was recorded with various annealing temperature (from 80 to 250 °C, 10 min). Surprisingly, TrFPy exhibited excellent ASE stability in an ambient condition, which is still detectable even after annealing at 250 °C for 10 min. The results suggest the pyrene‐capped molecular design strategy is positive on improving the optical gain stability and meanwhile maintaining excellent lasing properties.     

Low-Threshold,External-Cavity-Free Flexible Perovskite Lasers

A distinct advantage of halide perovskite semiconductors is their potential as gain media in high-performance, all-solution-processed flexible lasers. However, most perovskite microlasers employ external optical resonators with rigid and high-temperature/vaccum-processed structures unsuitable for flexible applications. Here, low-threshold, external-cavity-free perovskite lasers (≈550 nm, linewidth: ≈0.3 nm, quality factor: ≈1900, room temperature), prepared with excellent reproducibility using simple one-step spin-coating and low-temperature annealing, are demonstrated. Exceptionally low lasing thresholds of 9.3 and 14.6 µJ cm⁻² are achieved for external-cavity-free perovskite lasers on rigid and flexible substrates, respectively. The thresholds and quality factors are on par with that of high-performance perovskite microlasers with well-designed external cavities. The lasers exhibit good operational stability, showing half-life of >1.8 × 10⁸ pulses under optical pumping in air. Transient optical experiments reveal that the low thresholds stem from enhanced band-to-band spontaneous and stimulated emission processes in the high-quality microcrystalline perovskite, effectively out-pacing trap-mediated and Auger processes detrimental to the lasing action. The flexible perovskite lasers retain >95% of the initial intensity after 10000 bending cycles, showing outstanding mechanical durability. As these lasers can be produced from solution within minutes at low costs, the findings are expected to enable high-throughput, scalable fabrication of perovskite lasers for emerging applications.     

Centimeter‐Sized Cs4PbBr6 Crystals with Embedded CsPbBr3 Nanocrystals Showing Superior Photoluminescence: Nonstoichiometry Induced Transformation and Light‐Emitting Applications

An HBr‐assisted slow cooling method is developed for the growth of centimeter‐sized Cs₄PbBr₆ crystals. The obtained crystals show strong green photoluminescence with absolute photoluminescence quantum yields up to 97%. More importantly, the evolution process and structural characterizations support that the nonstoichiometry of initial Cs₄PbBr₆ crystals induce the formation of nanosized CsPbBr₃ nanocrystals in crystalline Cs₄PbBr₆ matrices. Furthermore, high efficiency and wide color gamut prototype white light‐emitting diode devices are also demonstrated by combining the highly luminescent Cs₄PbBr₆ crystals as green emitters and commercial K₂SiF₆:Mn⁴⁺ phosphor as red emitters with blue emitting GaN chips. The optimized devices generate high‐quality white light with luminous efficiency of ≈151 lm W⁻¹ and color gamut of 90.6% Rec. 2020 at 20 mA, which is much better than that based on conventional perovskite nanocrystals. The combination of improved efficiency and better stability with comparable color quality provides an alternative choice for liquid crystal display backlights.     

Photovoltaic and Amplified Spontaneous Emission Studies of High‐Quality Formamidinium Lead Bromide Perovskite Films

This study demonstrates the formation of extremely smooth and uniform formamidinium lead bromide (CH(NH₂)₂PbBr₃ = FAPbBr₃) films using an optimum mixture of dimethyl sulfoxide and N,N‐dimethylformamide solvents. Surface morphology and phase purity of the FAPbBr₃ films are thoroughly examined by field emission scanning electron microscopy and powder X‐ray diffraction, respectively. To unravel the photophysical properties of these films, systematic investigation based on time‐integrated and time‐dependent photoluminescence studies are carried out which, respectively, bring out relatively lower nonradiative recombination rates and long lasting photogenerated charge carriers in FAPbBr₃ perovskite films. The devices based on FTO/TiO₂/FAPbBr₃/spiro‐OMeTAD/Au show highly reproducible open‐circuit voltage (V_oc) of 1.42 V, a record for FAPbBr₃‐based perovskite solar cells. V_oc as a function of illumination intensity indicates that the contacts are very selective and higher V_oc values are expected to be achieved when the quality of the FAPbBr₃ film is further improved. Overall, the devices based on these films reveal appreciable power conversion efficiency of 7% under standard illumination conditions with negligible hysteresis. Finally, the amplified spontaneous emission (ASE) behavior explored in a cavity‐free configuration for FAPbBr₃ perovskite films shows a sharp ASE threshold at a fluence of 190 μJ cm^?2 with high quantum efficiency further confirming the high quality of the films.     

Metal Halide Perovskite Surfaces with Mixed A-Site Cations: Atomic Structure and Device Stability

Mixing cations in the perovskite structure has been shown to improve optoelectronic device performance and stability. In particular, Cs_xMA_1-xPbBr₃ (MA = CH₃NH₃) has been used to build high-efficiency light-emitting diodes. Despite those advantages, little is known about the exact location of the cations in the mixed perovskite film, and how cation distribution affects device properties and stability. By using scanning tunneling microscopy , the exact atomic structure of the mixed cation Cs_xMA_1-xPbBr₃ perovskite interface is revealed. In addition, X-ray photoelectron spectroscopy, ultraviolet photoemission spectroscopy and inverse photoemission spectroscopy are used to study the stability and electronic properties of the Cs_xMA_1-xPbBr₃ perovskite film. Partial substitution of MA⁺ by Cs⁺ induces a modification of the perovskite surface structure, leading to improved device stability is shown. These results provide a better understanding of the key parameters involved in the stability of mixed cation perovskite solar cells.     

Surface Defect Suppression for High Color Purity Light-Emitting Diode of Free-Standing Single-Crystal Perovskite Film

High color purity is one of the important features for single-crystal metal halide perovskite light-emitting diode (LED). Despite single-crystal perovskite showing low bulk defect concentration, single-crystal perovskite LEDs do not exhibit high color purity advantage due to the absence of effective surface defect passivation. Herein, one fully wrapped structure is proposed to passivate the surface of the free-standing CsPbBr₃ single-crystal films. The surface of CsPbBr₃ single-crystal films is wrapped by ultra-thin polymethyl methacrylate, precisely controlling the thickness. The single-crystal perovskite film device can achieve high color purity with a full width at half maximum (FWHM) of 15.8 nm) and a large luminescent area of 2.25 mm². It is observed that surface passivation is due to interaction of CO bond in polymer chains with the Lewis acid PbBr₂. The passivated perovskite single-crystal films significantly improve carrier lifetime and suppress surface defects. It is noteworthy that the passivated free-standing single-crystal perovskite films are feasible to build up a vertical LED device structure, avoiding the edge glowing and short-circuiting of the LED device. This study demonstrates the large luminescent area of the high-quality millimetre-scale free-standing single-crystal films for wide color gamut display and vertical optoelectronic devices.     

Solution-processed field-effect transistors based on polyfluorene –cesium lead halide nanocrystals composite films with small hysteresis of output and transfer characteristics

We have designed and investigated electrical and optical properties of solution-processed organic field-effect transistors (OFETs) based on conjugated polymer PFO and perovskite –cesium lead halide nanocrystals (CsPbI₃) composite films. It was shown that OFETs based on PFO:CsPbI₃ films exhibit current-voltage (I-V) characteristics of OFETs with dominant hole transport and saturation current behavior at temperatures 200–300 K. It was found that PFO:CsPbI₃ OFETs have a negligible hysteresis of output and transfer characteristics especially at temperatures below 250 K. The values of the hole mobility estimated from I-Vs of PFO:CsPbI₃ OFETs were found to be ∼2.4 10⁻¹ cm²/Vs and ∼1.9 10⁻¹ cm²/Vs in saturation and low fields regimes respectively at 300 K; the hole mobility dropped down to ∼6 10⁻³ cm²/Vs and 2.8 10⁻³ cm²/Vs respectively at 200 K, and then down to 5.5 10⁻⁵ cm²/Vs at 100 K (in low field regime), which is characteristic of hopping conduction. The effect of sensitivity to light and light-emitting effect were found under application of negative source-drain and gate pulse voltages to PFO:CsPbI₃ OFETs at 300 K. The mechanism of charge carrier transport in OFETs based on PFO:CsPbI₃ hybrid films is discussed.     

Self-Healing Lithographic Patterning of Perovskite Nanocrystals for Large-Area Single-Mode Laser Array

Lead halide perovskites exhibit extraordinary optoelectronic performances and are being considered as a promising medium for high-quality photonic devices such as single-mode lasers. However, for perovskite-based single-mode lasers to become practical, fabrication and integration on a chip via the standard top-down lithography process are strongly desired. The chief bottleneck to achieving lithography of perovskites lies in their reactivity to chemicals used for lithography as illustrated by issues of instability, surface roughness, and internal defects with the fabricated structures. The realization of lithographic perovskite single-mode lasers in large areas remains a challenge. In this work, a self-healing lithographic patterning technique using perovskite CsPbBr₃ nanocrystals is demonstrated to realize high-quality and high-crystallinity single-mode laser arrays. The self-healing process is compatible with the standard lithography process and greatly improves the quality of lithographic laser cavities. A single-mode microdisk laser array is demonstrated with a low threshold of 3.8 µJ cm⁻². Moreover, the control of the lasing wavelength is made possible over a range of up to 6.4 nm by precise fabrication of the laser cavities. This work presents a general and promising strategy for standard top-down lithography fabrication of high-quality perovskite devices and enables research on large-area perovskite-based integrated optoelectronic circuits.     

Piezoelectric Nanogenerator Based on In Situ Growth All-Inorganic CsPbBr3 Perovskite Nanocrystals in PVDF Fibers with Long-Term Stability

Inorganic lead halide perovskite has become an emerging material for modern photoelectric and electronic nanodevices due to its excellent optical and electronic properties. In view of its huge dielectric and electrical properties, inorganic CsPbBr₃ perovskite is introduced into the piezoelectric nanogenerator (PENG). Based on one-step electrospinning of solutions containing CsPbBr₃ precursors and polyvinylidene difluoride (PVDF), in situ growth of CsPbBr₃ nanocrystals in PVDF fibers (CsPbBr₃@PVDF composite fibers) with highly uniform size and spatial distribution are synthesized. The CsPbBr₃@PVDF composite fibers based PENG reveals an open-circuit voltage (V_oc) of 103 V and a density of short-circuit current (I_sc) of 170  µ A cm⁻², where the V_oc is comparable to the state-of-the-art hybrid composite piezoelectric nanogenerators (PENGs) and the density of I_sc is 4.86 times higher than that of lead halide perovskites counterpart ever reported. Moreover, CsPbBr₃@PVDF composite fibers based PENG exhibits fundamentally improved thermal/water/acid–base stabilities. This study suggests that the CsPbBr₃@PVDF composite fiber is a good candidate for fabricating high-performance PENGs, promising application potentials in mechanical energy harvesting and motion sensing technologies.     

Highly Controlled Zigzag Perovskite Nanocrystals Enabled by Dipole-Induced Self-Assembly of Nanocubes for Low-Threshold Amplified Spontaneous Emission and Lasing

Self-assembly of nanocrystals into controlled structures while uncompromising their properties is one of the key steps in optoelectronic device fabrication. Herein, zigzag CsPbBr₃ perovskite nanocrystals are demonstrated with a precise number of components with nanocube morphology, these can be successfully obtained through a dipole-induced self-assembly process. The addition of a trace amount of deionized water facilitates the transfer from CsPbBr₃ nanocubes to intermediates of CsPb₂Br₅ and Cs₃In₂Br₉, which then fastly release reaction monomers leading to further homogenous nucleation of CsPbBr₃ nanocubes, followed by the formation of zigzag CsPbBr₃ nanocrystals through a dipole-induced self-assembly process. Dipole moment along <110> axis is found to be the driving force for the assembly of nanocubes into zigzag nanocrystals. The zigzag CsPbBr₃ nanocrystals exhibit desirable optical properties comparable to their nanocube counterparts and offer advantages for amplified spontaneous emission and lasing applications with low pump thresholds of 3.1 and 6.02 µJ cm⁻², respectively. This study not only develops a strategy for producing highly controlled zigzag perovskite nanocrystals and provides insights on the dipole-induced self-assembly mechanisms, but also opens an avenue for their application in lasing.     

Low‐Threshold Distributed‐Feedback Lasers Based on Pyrene‐Cored Starburst Molecules with 1,3,6,8‐Attached Oligo(9,9‐Dialkylfluorene) Arms

Here, a detailed characterization of the optical gain properties of sky‐blue‐light‐emitting pyrene‐cored 9,9‐dialkylfluorene starbursts is reported; it is shown that these materials possess encouragingly low laser thresholds and relatively high thermal and environmental stability. The materials exhibit high solid‐state photoluminescence (PL) quantum efficiencies (>90%) and near‐single‐exponential PL decay transients with excited state lifetimes of ～1.4 ns. The thin‐film slab waveguide amplified spontaneous emission (ASE)‐measured net gain reaches 75–78 cm^?1. The ASE threshold energy is found to remain unaffected by heating at temperatures up to 130 °C, 40 to 50 °C above T_g. The ASE remained observable for annealing temperatures up to 170 or 200 °C. 1D distributed feedback lasers with 75% fill factor and 320 nm period show optical pumping thresholds down to 38–65 Wcm^?2, laser slope efficiencies up to 3.9%, and wavelength tuning ranges of ～40 nm around 471–512 nm. In addition, these lasers have relatively long operational lifetimes, with N_1/2 ≥ 1.1 × 10⁵ pulses for unencapsulated devices operated at ten times threshold in air.     

An Interdiffusion Method for Highly Performing Cesium/Formamidinium Double Cation Perovskites

The fabrication of high‐quality cesium (Cs)/formamidinium (FA) double‐cation perovskite films through a two‐step interdiffusion method is reported. Cs_x FA_1‐x PbI_{3‐y(1‐x )}Br_{y(1‐x )} films with different compositions are achieved by controlling the amount of CsI and formamidinium bromide (FABr) in the respective precursor solutions. The effects of incorporating Cs⁺ and Br^? on the properties of the resulting perovskite films and on the performance of the corresponding perovskite solar cells are systematically studied. Small area perovskite solar cells with a power conversion efficiency (PCE) of 19.3% and a perovskite module (4 cm²) with an aperture PCE of 16.4%, using the Cs/FA double cation perovskite made with 10 mol% CsI and 15 mol% FABr (Cs_0.1FA_0.9PbI_2.865Br_0.135) are achieved. The Cs/FA double cation perovskites show negligible degradation after annealing at 85 °C for 336 h, outperforming the perovskite materials containing methylammonium (MA).     

Hierarchical Chiral Self-Assembly of Lead Halide Perovskite Nanocrystals by Oriented Phase Transition

Self-assembly of lead halide perovskite nanocrystals (NCs) into close-packed, long-range-ordered nanostructures can effectively modulate their photoelectronic properties, yet significantly challenging. Herein, an efficient approach is reported to induce the hierarchical self-assembly of perovskite CsPbBr₃ NCs by phase transition using chiral cysteine ligands, yielding asymmetric Cs₄PbBr₆ nanorods (NRs) with the circularly polarized luminescent response. An interfacial phase transition process is found during the conversion of CsPbBr₃ nanocubes to Cs₄PbBr₆ NCs initiated by cysteine molecules. Then the Cs₄PbBr₆ NCs aggregate sequentially to form nanoclusters, which further self-assemble into the chiral Cs₄PbBr₆ NRs. Molecular dynamics simulations reveal that the Cs₄PbBr₆ nanochains gradually approach each other to achieve an asymmetric structure, and the simulated circular dichroism spectrum further supports the formation of a chiral structure. This work offers a facile method for the hierarchical chiral self-assembly of lead halide perovskite nanostructures, which brings new insights to explore chiral nanostructures by modulating the surface chemistry and post self-assembly.     

Solution‐Processed Low Threshold Vertical Cavity Surface Emitting Lasers from All‐Inorganic Perovskite Nanocrystals

Recently, newly engineered all‐inorganic cesium lead halide perovskite nanocrystals (IPNCs) (CsPbX₃, X = Cl, Br, I) are discovered to possess superior optical gain properties appealing for solution‐processed cost‐effective lasers. Yet, the potential of such materials has not been exploited for practical laser devices, rendering the prospect as laser media elusive. Herein, the challenging but practically desirable vertical cavity surface emitting lasers (VCSELs) based on the CsPbX₃ IPNCs, featuring low threshold (9 µJ cm^?2), directional output (beam divergence of ≈3.6°), and favorable stability, are realized for the first time. Notably, the lasing wavelength can be tuned across the red, green, and blue region maintaining comparable thresholds, which is promising in developing single‐source‐pumped full‐color visible lasers. It is fully demonstrated that the characteristics of the VCSELs can be versatilely engineered by independent adjustment of the cavity and solution‐processable nanocrystals. The results unambiguously reveal the feasibility of the emerging CsPbX₃ IPNCs as practical laser media and represent a significant leap toward CsPbX₃ IPNC‐based laser devices.