Single-Mode Lasers Based on Cesium Lead Halide Perovskite

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Single-Mode Lasers Based on Cesium Lead Halide Perovskite Sub-Micron Spheres Bing Tang, Hongxing Dong, Liaoxin Sun, Weihao Zheng, Qi Wang, Fangfang Sun, Xiongwei Jiang, Anlian Pan, and Long Zhang ACS Nano, Just Accepted Manuscript • DOI: 10.1021/acsnano.7b04496 • Publication Date (Web): 09 Oct 2017 Downloaded from http://pubs.acs.org on October 11, 2017

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Single-Mode Lasers Based on Cesium Lead Halide Perovskite Sub-Micron Spheres ‖

Bing Tang† , Hongxing Dong†*, Liaoxin Sun‡, Weihao Zheng§, Qi Wang‡, Fangfang Sun‡, Xiongwei Jiang†, Anlian Pan§, Long Zhang†#* † Key Laboratory of Materials for High-Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai, 201800, China ǁ University of Chinese Academy of Sciences, Beijing, 100049, China ‡ National Lab for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, 200083, China § Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, and School of Physics and Electronics, Hunan University, Changsha, 410082, China # IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai, 200240, China

Corresponding Author *E-mail: [email protected]; [email protected]

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ABSTRACT

Single-mode laser is realized in a cesium lead halide perovskite sub-micron sphere at room temperature. All-inorganic cesium lead halide (CsPbX3, X = Cl, Br, I) microspheres with tunable sizes (0.2~10 µm) are firstly fabricated by a dual-source chemical vapor deposition method. Thank to smooth surface and regular geometry structure of microsphere, whispering gallery resonant modes benefit a single-mode laser realized in a sub-micron sphere. Surprisingly, singlemode laser with a very narrow linewidth (~0.09 nm) was achieved successfully in the CsPbX3 spherical cavity at low threshold (~0.42 µJ cm-2) with a high cavity quality factor (~6100), which are the best specifications of lasing modes in all the natural nano/microcavities ever been reported. By modulating the halide composition and sizes of the microspheres, the wavelength of single-mode laser can be continuously tuned from red down to the violet color (425-715 nm). This work illustrates that the well-controlled synthesizing metal cesium lead halide perovskite nano/microspheres may offer an alternative route to produce a widely tunable and greatly miniaturized single-mode laser.

KEYWORDS: Single-mode laser, Cesium lead halide, Whispering gallery mode, Microsphere, Wavelength tunable


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Miniaturized semiconductor lasers have been a significant research subject due to their promises for the integration of nanoscale photonic and optoelectronic circuits and devices.1-3 In the past two decades, tremendous research efforts have been devoted to the development of high quality semiconductor lasers with broadband tunability and controllable output wavelength. Especially, the semiconductor lasers oscillated at a single frequency, such as single-mode lasers, have attracted great interests because of their practical applications in on-chip optical processing, communication and data storage. However, most of the reported semiconductor lasers are subject to random fluctuations and instabilities due to lack of mode selection mechanism.4-7 The realization of single-mode lasing with small mode volume, narrow spectral linewidth and a broadband tunability is still a great challenge. Generally, single-mode laser could be obtained through the use of distributed Braggreflector (DBR) mirrors or distributed feedback (DFB) structures on nanostructures.8 Unfortunately, only Q. Zhang et al reported single-mode CdS nanoribbons laser realized in this way recently, others still stay in the theoretical simulation due to the difficulties in the fabrication of such multi-nanostructures.9 Additionally, single-mode lasing can also be observed through the Vernier effect in two or more coupled laser cavities, which mainly relies on the sophisticated nano-manipulation and fabrication techniques.10-13 Facing to these problems, the straightforward way to obtain single-mode laser is reducing the optical path of the laser cavity to keep only one mode surviving in the bandwidth of the optical gain. As one of representative reports, J. Li et al obtained single-mode ZnO lasing from individual submicron-sized rod with diameter of about 600 nm.14 However, the reduction of cavity size will usually increase the optical loss, resulting in high threshold and low cavity quality factor for lasing action. To compensate the loss caused by the shortening optical path, some materials with high optical gain and nano/microcavities with


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good optical confinement are highly desirable to achieve single-mode lasing with good performance. Recently, lead halide perovskites have gained great attention for their big success in photovoltaic.15-17 As a direct band-gap semiconductor, the long carrier lifetimes and diffusion lengths, the low non-radiative recombination rates and the high photoluminescence quantum yield make this kind of material particularly attractive for laser applications.18-21 Compared to organic-inorganic hybrid perovskite, all-inorganic perovskite (such as cesium lead halide) exhibits better stability without losing its superior optoelectronic properties.22,23 Indeed, perovskite lasers have been achieved in many nano/microstructures with different geometries, such as nanowires,24-26 nanoplatelets,27-29 nanorods,30 and quantum dots,31,32 but a low threshold, narrow laser width and wide-band tunable single-mode laser spanning the full visible region has never been reported. As we mentioned above, besides the high optical gain, a tightly confined optical mode in sub-micron cavity is crucial to the performance of single-mode laser. Here we note that the light confined in WGM microcavities (cross-section of microwire, nanoplatelets) usually present a better quality factor than that of Fabry-Pérot (F-P) type nanowire or nanorod cavities because of total internal reflection effect in WGM microcavities.33,34 With this in mind, the synthesis of the perovskite sub-micron structures worked as WGMs could be a promising route to achieve a single-mode laser with good performance. In this work, we firstly report a tunable single-mode lasing in all-inorganic cesium lead halide (CsPbX3, X = Cl, Br, I) sub-micron spheres at room temperature, which were synthesized by a simple-step vapor transport processing. The single-mode laser with very narrow linewidth (~0.09 nm) is realized in the perovskite sub-micron spherical cavity at low threshold (~0.42 µJ cm-2) with high cavity quality factor (~6100), even in such sub-micron sphere. Additionally,


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combining element modulation and size control, high quality single-mode lasing can be extended to the whole visible spectra region. Results and Discussion Cesium lead halide CsPbX3 (X = Cl, Br, I) microspheres (MSs) were grown by a simple dual-source chemical vapor deposition method using CsX and PbX2 powders as source material and bared silicon wafer as substrate in a horizontal tube furnace. Similar to the growth of other semiconductor microspheres, the formation of the spherical shape mainly due to the surface tension forces at high temperature.35-37 Figure 1a shows a typical SEM image of synthesized samples. It can be seen that the as-grown CsPbI3 MSs dispersed on a piece of silicon wafer with diameters ranging from 0.2 to 1.0 µm, placing them in an ideal size regime for single-mode lasing as confirmed later. The upper-right inset of Figure 1a clearly shows perfectly spherical morphology and very smooth surface of the CsPbI3 MSs. Moreover, varying the deposition temperature and/or the position of silicon substrate, the diameters of the CsPbI3 MSs can be further increased to several micrometers, as shown in Figure S1a. For a widely tunable singlemode laser, similar MS structures of CsPbX3 (X = Cl, Br) were also obtained by halogen substitution, with diameter controlled around 1.0 µm as shown in Figure S1b and S1c. PL images of CsPbX3 MSs are shown in Figure S2. The preparation details are presented in experimental section and Table S1. Figure 1b presents a typical TEM image of an individual CsPbI3 MS, confirming its spherical structure inferred from the relatively uniform contrast of the MS. Furthermore, the high-resolution TEM (HRTEM) image in Figure 1c showing continuous lattice fringe along the whole surface without apparent grain boundaries, reveals the cubic structure of CsPbI3 MS, in good agreement with the corresponding FFT pattern in Figure 1d. The microsphere with high crystalline quality also can be confirmed by similar SAED patterns in


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Figure S3 taken from different positions on an individual CsPbBr3 MS. Additionally, the chemical composition and uniform spatial distribution of corresponding elements over the whole CsPbX3 MSs were confirmed by the energy dispersive X-ray spectroscopy (EDS) mapping (Figure 1e, 1f, 1g). Optical properties of the as-prepared CsPbX3 MSs were characterized with a confocal microphotoluminescence spectrometer. As the bandgap of CsPbX3 perovskites largely determined by the hybridization states of Pb and X orbitals, band-gap engineering can be achieved via halogen substitution, especially, by controlling the Cl/Br or Br/I ratio to continuously tune emission wavelength covering the entire visible spectrum. The PL spectra were measured on the CsPbX3 MSs at room temperature (Figure 1h), from which three strong, narrow peaks at 427, 527 and 702 nm were obtained, respectively. The upper insets of Figure 1h clearly present the PL images of these synthesized CsPbX3 MSs recorded at low excitation density, showing uniform blue, green and red emissions from MS bodies. Furthermore, the excellent optical properties of these CsPbX3 microcrystals could be inferred from their PL spectra, exhibiting relatively small full width at half maximum (FWHM) with 11, 13, and 20 nm, respectively. All these characterizations confirm high quality CsPbX3 microspheres with perfectly spherical shape, highly smooth surface, and well controllable size, making them maybe ideal WGM cavity candidates for single-mode lasers. Optically pumped lasing experiments were performed in a vacuumed atmosphere at room temperature. As schematically presented in Figure 2a, a 400 nm fs-laser was used as the excitation light source. The laser spot covered the whole MS to ensure its homogenous excitation. The green circle indicates the light propagation inside the MS WGM cavity. Figure 2b shows typical excitation-power-dependent PL spectra of one single CsPbBr3 MS with diameter


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about 780 nm. It can be seen that a single broad emission peak resulted from spontaneous emission was observed at ~530 nm with a FWHM of δλ = 16.6 nm, as pump density was below the threshold of 0.42 µJ cm-2. When pump density exceeded the threshold, one single sharp peak abruptly appeared above the spontaneous emission background and grew drastically with further increasing pump density. Importantly, no other resonant peaks were found in this process. A clear evolvement from spontaneous emission to stimulated emission occurs in the CsPbBr3 MS, indicating the achievement of single-mode laser. Simultaneously, it can be noticed that the broadening of the full width at half maximum of the lasing peak (0.09-0.62 nm) occurs with increasing of the excitation power due to highly injected carriers density, which may induced variation of refractive index of materials and thus the shift of cavity modes during dynamical process of stimulated emission for pulsing laser.38,39 The PL microscopy optical image of this corresponding MS above the lasing threshold is shown in the upper inset of Figure 2b. The interference pattern was produced by the coherent light emission in the MS WGM microcavity, confirming the generation of stimulated radiation. And, a slight blueshift (~0.5 nm) could also be observed in CsPbBr3 MSs with pump density increasing, which may be caused by the band filling effect and/or the reduction of refractive index.40,41 Figure 2c shows the dependence of emission intensity on the excitation power. A typical “S” shaped curve can be observed, confirming the evolution from random spontaneous emission to amplified spontaneous emission at ~0.42 µJ cm-2, then finally simulated emission taking over at ~0.77 µJ cm-2. To further analyze the characteristics of single-mode lasing, a representative full lasing spectrum taken at ~0.42 µJ cm-2 was presented in Figure 2d. The peak was well fitted by a Lorentz function with FWHM of 0.09 nm. Using the relationship Q = λ/δλ, where λ is the peak center wavelength and δλ is the peak width, the cavity quality factor Q is calculated to be ~6100. Interestingly, we found that


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lasing linewidth, lasing threshold and the cavity quality factor Q in such a sub-micron sphere are better than those of other nano/micro-sized lasers reported in previous literatures (Table 1). Generally, the Q factor of a traditional dielectric microcavity decreases drastically due to the more radiation loss in a smaller cavity, which also leads to a higher lasing threshold.14,42 In our work, the good performance of such small CsPbBr3 MSs can be attributed to nearly perfect naturally formed spherical WGM cavity and high optical gain material. In our regular microsphere WGM microcavities, there are no such corner optical losses, and three-dimensional confinement of light due to the total internal reflection is successfully achieved. And, compared to other nano/microstructure optical cavities, of which most part lays on the substrate, the coupling between CsPbX3 MS cavity and substrate is comparatively very weak, resulting in less optical losses.43 Perhaps, as with these properties, the spherical microcavities can exhibit a better quality factor. Further investigations about the dynamics of single mode lasing in CsPbBr3 MSs were conducted by time-resolved photoluminescence (TRPL) using a 400 nm fs-laser and a streakcamera system. Figure 3a shows the typical streak camera images of CsPbBr3 MS recorded at the pump density of 0.1 PTh and 1.2 PTh, respectively. It can be clearly seen that a typical wide spontaneous emission decay with a broad emission band and long decay time changes into a narrow emission peak with a short decay time when the pump density increasing from 0.1 PTh to 1.2 PTh. As shown in Figure 3b, at low excitation density (0.1 PTh, 0.9 PTh), a deconvolution biexponential decay function with rapid and slow components can be used to simulate the decay curves. Based on previous reports, rapid and slow components can be attributed to surface state and bulk recombination, respectively.23 Worth noting, slight difference of lifetime was observed between 0.1 PTh (195.2±2.5 ps, 60.4%; 749.1±6.1 ps, 39.6%) and 0.9 PTh (143.3±1.3 ps, 77.6%;


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669.3±7.6 ps, 22.4%), indicating that there is only a fraction of nonradiative recombination in such low excitation density. As the pump density increasing to 1.2 PTh, an additional decay component is observed (30.5±0.9 ps, 95.3%), which contributes far more than other two components (125.0±0.9 ps, 3.9%; 608.0±12.6 ps, 0.8%), implying the occurrence of an effective stimulated emission process. Considering the blueshift (~0.5 nm) of CsPbBr3 laser in Figure 2b, the EHP mechanism is responsible for simulated emission, similar to other CsPbBr3 nanostructure lasing.23,44,45 Additionally, to probe the stability of lasing output, the CsPbBr3 MS was constantly pumped by pulsed excitation source. One single CsPbBr3 MS was pumped constantly by 400 nm pulsed laser (~40 fs, 10 kHz) under ambient conditions (21 oC, 45% relative humidity) at an excitation density of 1.2 PTh. The integrated emission intensity of CsPbBr3 MS has been recorded and plotted as a function of excitation time in Figure 3c, in which stable lasing output can be observed for over 50 minutes (~3×107 laser shots). And the emission intensity of lasing peak is observed to be very weak until 4.2×107 excitation cycles. The results illustrated that the CsPbBr3 MSs have significant operating lifetimes under ambient conditions. To further investigate the modulation of the single-mode laser with different microcavity diameters, we performed laser emission measurements for a set of CsPbBr3 MSs with different diameters varied about 780 nm. As shown in Figure 4a, the single-mode lasing emission can be tuned from 533.8 to 545.2 nm. In general, the resonant modes of a spherical WGM microcavity can be simply expressed as:33,34 πD/(λ/N) ≈ ν

(1)

where D denotes the diameter of CsPbBr3 MS; λ is the wavelength of the resonant peak; ν and N are the mode orders and the refractive index of the medium, respectively. In our


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experiment, the size of sub-micron sphere varies very small and only one lasing mode survives in gain region, so the mode order is unchanged and thus the resonant wavelength is linearly proportional to the diameter of the spherical WGM microcavity. To further understand the single-mode laser behavior of the spherical WGM microcavity, theoretical simulation by using Finite domain time difference (FDTD solution) package was performed, where the dispersion of refractive index of CsPbBr3 was employed.46 Considering the diameters (~780 nm) of MSs, the simulated transverse magnetic-polarized (TM-polarized) whispering gallery modes can well match with the experimental results, here we note that the preferred TM polarized lasing modes are consistent with the results from cesium lead halide perovskite nanoplatelets.27 The singlemode laser peaks with a diameter dependence are also plotted as shown in Figure 4b. The lasing emission peaks shows a linearly red shift with increasing of the diameters of the CsPbBr3 MS cavities, as we expected from equation (1). The electric field distributions of laser (λ = 545.2 nm) in MS is also shown in inset of Figure 4b, the typical WGM E-filed pattern can be clearly observed. Besides, the electric field distributions for lasing peaks (λ = 533.8, 537, 539, 542.4 nm) are presented in Figure S4. The size of microcavity is not only critical to the wavelength of laser resonance, but also affects the number of resonant peaks. As shown in Figure S5, multimode lasing could also be observed around 535 nm when the size of the microcavity increases to 12.9 µm. Single-mode lasing emission with high cavity quality factor Q, stable and spectrally narrow peak in the entire visible region are firstly achieved through element modulation of cesium lead halide MSs. Figure 5 shows the typical lasing spectra and corresponding PL images. It can be clearly seen that tunable single-mode laser has been made ranging from 425 nm to 715 nm. And, the clearly spatial interference patterns of the PL images (upper insets of Figure 5) above lasing


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threshold show the predominance of WGM lasing in spherical microcavities. Although the size of the MS was reduced to about 1 µm to obtain the single-mode laser, the laser linewidth, threshold and cavity quality factor exhibit surprisingly good performance. Moreover, to further investigate the single-mode lasing properties, we use the nanosecond laser (532/355-nm Switch, 15 kHz, 1.1 ns) as the excitation source. And, considering the possible thermal effects of nanosecond lasers,47 our laser experiments are performed at liquid nitrogen temperature. The corresponding results are shown in Figure S6. It can be seen that a tunable single-mode laser with narrow linewidth (~0.1 nm) also can be obtained in the entire visible region (450-720 nm). Interestingly, the cavity quality factor can be as high as ~6200. The lasing threshold is 1.65 µJ cm-2. Interestingly, we found that the threshold (0.22 µJ cm-2) obtained under femtosecond excitation (532 nm, 40 fs) is much lower than that under nanosecond excitation (532 nm, 1.1 ns), as shown in Figure S7. Similar results that a decrease of lasing threshold with a decrease of pulse duration were also found in other studies. The reason may be that the evolution of the density of excited states and consequently the gain profiles will be different under various pulse excitation.48 These results further illustrate that the achieved cesium lead halide MSs may be a good candidate for the development of single-mode laser devices. Conclusion We have realized single-mode laser in individual all-inorganic cesium lead halide CsPbX3 sub-micron spheres worked as WGM microcavities at room temperature. The perovskite MSs of CsPbX3 were prepared by a simple vapor transport method. The perfect smooth surface and regular geometry structure ensure that the as-grown perovskite MSs can be formed as ideal WGM optical cavities. Significantly, single-mode laser was successfully achieved in one single MS with low threshold (~0.42 µJ cm-2). And, by modulating the halide composition and the sizes


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of the MSs, the single-mode lasing emission can be continuously tuned over the entire visible range. More importantly, single-mode laser with narrow linewidth (~0.09 nm) can be obtained in such a small diameter (D < 1 µm) cavity with high cavity quality factor (~6100), which is the best performance in all the reported natural nano/microcavity lasers. Methods Synthesis of CsPbX3 perovskite MSs and Structural Characterizations: In our experiment, CsPbX3 microspheres were synthesized in a conventional horizontal tube furnace. All regents were used without further purification, which were directly purchased from Sigma-Aldrich. The composition of vapor source is CsX and PbX2 powders with molar ratio 1:2, of which the sum of the total weight is controlled around 0.15 g. At first, the lead (II) halide powder (PbX2, 99.999%, Sigma-Aldrich) was placed in the upper stream position of quartz furnace, which was approximately 4 cm from center of the quartz tube. Secondly, the cesium halide powder (CsX, Aldrich, 99.999%, Sigma-Aldrich) was placed in the center of the furnace. Then, three silicon substrates (1cm × 1.4 cm) were placed 8 cm away from the center in the downstream, which were cleaned by distilled water and acetone before. The quartz tube was sealed by vacuum grease and firstly pumped to 0.5 Torr, followed by a 60 sccm flow of argon for 15 min to exhaust the atmosphere. The temperature of the tube furnace was raised to 900 K (870 for CsPbI3, 890 K for CsPbBr3, 920 K for CsPbCl3) for over 20 min, with argon flow controlled at 30 sccm. After 30-60 min of reaction, the system was cooled down to room temperature naturally. The morphologies, structures and composition of the products were characterized by field-emission scanning electron microscopy (FE-SEM; Auriga S40, Zeiss, Oberkochen, Germany) and highresolution transmission electron microscopy (HRTEM, JEOL-2010).


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Optical Characterizations and Numerical Calculation: The optical properties of the CsPbX3 MSs were measured at room temperature in a vacuumed atmosphere using a confocal microphotoluminescence system (LabRAM HR Evolution). A multichannel air cooled (-60 oC) CCD detector (Syncerity OE) with resolution~0.0166 nm was used for lasing measurement. The room temperature photoluminescence and lasing emission spectra were all collected by the same objective (50X, NA: 0.5), and spectrally resolved using a monochromator. To further explore the characteristic of single-mode lasing, an isolated CsPbBr3 MS was selectively excited by a 400 nm fs-laser, which was obtained through a BBO crystal from the amplifier laser source (Libra, Coherent, ~40 fs, 10 kHz) and a solid state diode laser (532/355-nm Switch, 15 kHz, 1.1 ns, Crystal, 2Q-STA-IL, Germany). A 400 nm fs-laser (repetition rate of 1 KHz, pulse width of 80 fs) equipped with a streak camera (C10910, Hamamatsu) was used to perform time resolved PL measurements. A BBO crystal was used to generate 400 nm output from 800 nm laser of a regenerative amplifier (SPTF-100F-1K-ACE, Spectra-Physics). The TRPL decay profile can be fitted by a deconvolution multiexponential decay function with a IRF (Impulse Response Function) of 180 ps. Additionally, the lasing mode properties including mode orders and E-filed distributions of MSs were calculated by using finite element method (FDTD solution). During simulation process, a dipole source is used, PML (perfectly matched layer) is chosen as boundary condition, the refractive index of materials is 2.4, the maximum mesh step is set as 4 nm, and the monitored wavelength is from 450 nm to 600 nm.

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Figure 1. Characterizations of cesium lead halide MSs. (a) Typical SEM image of the CsPbI3 MSs. Top inset: magnified image of an individual CsPbI3 MS. Bottom inset: PL image of asgrown CsPbI3 MSs excited by 457 nm continuous wave laser at room temperature. (b) TEM image of an individual CsPbI3 MS. High resolution TEM (HRTEM) image (c) and the corresponding fast Fourier transform (FFT) pattern (d) from the individual CsPbI3 MS. EDS elemental mapping for CsPbI3 (e), CsPbBr3 (f), CsPbCl3 (g), showing the composition of the MSs. (h) Photoluminescence (PL) spectra of CsPbCl3, CsPbBr3, CsPbI3 MSs. Inset: PL images of CsPbCl3, CsPbBr3, and CsPbI3 MS (left to right).


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Figure 2. Single-mode lasing from an individual CsPbBr3 MS. (a) Schematic of an individual CsPbBr3 MS on silicon substrate pumped by 400 nm laser excitation (~40 fs, 10 kHz). The green circle indicates the light propagation inside the spherical WGM cavity. (b) Excitation powerdependent lasing spectra from one single CsPbBr3 MS. Inset: PL image of CsPbBr3 MS above lasing threshold. (c) Integrated emission intensity as a function of pump density showing the lasing threshold at ~0.42 µJ cm-2. (d) Lorentz fitting of a lasing oscillation mode. The FWHM of the lasing peak (δλ) is 0.09 nm, corresponding to a Q factor ~6100.


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Figure 3 Lifetime and stability measurements of one single CsPbBr3 MS. (a) The streak camera image of an isolated CsPbBr3 MS at the pump density of 0.1 PTh (upper inset) and 1.2 PTh (bottom inset). (b) Typical PL decay curve obtained at three different excitation density (0.1 PTh, 0.9 PTh, 1.2 PTh). (c) Integrated emission intensity of a CsPbBr3 MS under 400 nm fs-laser excitation at a constant pump density of 1.2 PTh while exposed to ambient atmosphere.


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Figure 4. Single-mode lasing characterization and theoretical simulation on CsPbBr3 MSs with diameter around 780 nm. (a) Single-mode lasing spectra of five typical CsPbBr3 MSs with different diameters. (b) The resonant mode is extracted and plotted as function of the diameter of CsPbBr3 MS. Top inset: Simulated electric field distribution under a transverse magnetic resonant mode at 545.2 nm.


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Figure 5. Multicolor single-mode lasers and the corresponding emission images of one single CsPbX3 MS.


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Table 1. Comparisons of main laser parameters among reported semiconductor nano/microlasers on natural nano/microcavities.

Material

Peak

Linewidth

(nm)

(nm)

ZnSe NW

461

0.72

GaN NP

369

ZnO NW

Q-factor

Threshold at RT (µJ cm-2)

Excitation source

Reference

640

~340

150 fs, 1 kHz

49

2.20

170

~40000

0.5 ns, 1 kHz

50

387

0.80

484

~400

8 ns, 10 Hz

51

ZnO ND

389

0.70

556

~750

8 ns, 10 Hz

42

CdS NW

512

0.40

1280

~14

120 fs, 1 kHz

52

MAPbIaCl3-a NW

744.4

1.60

372

~60

50 fs, 1 kHz

53

CsPbBr3 NW

538

0.26

2069

~6.2

100 fs, 250 kHz

24

CsPbBr3 NR

543

0.155

3500

~14.1

100 fs, 1 kHz

30

CsPbCl3 NW

420

0.30

1400

~7

150 fs, 100 kHz

22

MAPbI3 NW

787

0.22

3600

~0.6

100 fs, 250 kHz

20

CsPbBr3 NPL

536

0.15

3600

~2.2

50 fs, 1 kHz

27

FAPbI3 NPL

837

0.49

1700

~25

100 fs, 250 kHz

28

FAPbI3 NW

824

0.53

1554

~6.2

100 fs, 250 kHz

26

CsPbBr3 MS

545.2

0.09

6100

~0.42

40 fs, 10 kHz

This Work

Table 1 Footnote. MA, FA, NW, NP, ND, NR, NPL, and RT denote CH3NH3, CH(NH2)2 nanowire, nanopillar, nanodisk, nanorod, nanoplatelet, and room temperature respectively.


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ASSOCIATED CONTENT Acknowledgements This work was supported financially by the NSFC (61378074, 61675219, 61475173, 11474297, 11674343, 51525202). H. Dong and L. Sun acknowledges Youth Innovation Promotion Association CAS and Shanghai Science and Technology Foundation (Grant No. 17ZR1444000). Supporting Information. The Supporting Information is available free of charge via the Internet at http://pubs.acs.org. (PDF) A: SEM images of CsPbI3, CsPbBr3, CsPbCl3 MSs. B: PL images of CsPbI3, CsPbBr3, CsPbCl3 MSs. C: TEM analysis on an individual CsPbBr3 MS. D: Electric field intensity distribution simulation study in different CsPbBr3 MSs. E: Multi-mode lasing spectra for CsPbBr3 MS. F: Single-mode lasing from CsPbX3 MS at 77 K. G: Single-mode lasing from CsPbI3 MS at 77 K excited by 532 nm fs-laser. H: Detailed reaction conditions for the synthesis of CsPbX3 MSs.

Author Contributions B. T and H. D have designed and performed the experiments during the whole process. L. S, Q. W, and F. S helped to solve some technical problems. W. Z and A. P helped to finish the experiment of time-resolved photoluminescence. B. T, H. D, and L. S wrote and revised the paper. X. J and L. Z supervised the project and conceived the study. The manuscript was written


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through contributions of all authors. All authors have given approval to the final version of the manuscript.


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The table of contents We have realized single-mode lasers in individual all-inorganic cesium lead halide CsPbX3 (X = Cl, Br, I) sub-micron spherical WGM microcavities at room temperature. Multicolor singlemode laser with a very narrow linewidth (~0.09 nm) was achieved successfully in such a submicron spherical (D < 1 µm) cavity with high cavity quality factor (~6100) at low threshold (~0.42 µJ cm-2), which is the best in all the reported natural nano/microcavity lasers.

400 nm fs-laser 545 nm Emission

Silicon Perovskite WGM Cavity


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Single-Mode Lasers Based on Cesium Lead Halide Perovskite

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