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PurposeThis article aims to draw a conceptual model that integrates the view from the entrepreneurial event model with entrepreneurial education and prior self-employment experience. The model tests the role of entrepreneurial education on the formation of intentions to become an entrepreneur and examines whether prior self-employed experiences moderate the route from entrepreneurial education, entrepreneurial perceived feasibility (PF) and perceived desirability (PD) into the entrepreneurial intention (EI).Design/methodology/approachThe authors operated on a sample of 389 master's students by applying Cronbach's alpha, exploratory factor analysis, confirmatory factor analysis and structural equation modelling to illustrate the links between constructs.FindingsThe study found that entrepreneurial education is positively correlated with PF, PD, and intention to enter entrepreneurial activities. PD is determined as a partial mediator in the entrepreneurial education–intention link and full mediator in PF and EI. Moreover, the study revealed that prior self-employed experiences serve as a positive moderator in the path from entrepreneurial education and PD to EI.Practical implicationsThe study offers several recommendations based on research findings so as to nurture and promote entrepreneurial activities among master's students.Originality/valueThe current research provides novel insights about the relationship between entrepreneurial education and intentions to become an entrepreneur over and about the central antecedents in the entrepreneurial event model and moderation effects of prior self-employed experiences.

Reconfigurable metamaterials require constituent nanostructures to demonstrate switching of shapes with external stimuli. Yet, a longstanding challenge is in overcoming stiction caused by van der Waals forces in the deformed configuration, which impedes shape recovery. Here, we introduce stiff shape memory polymers. This designer material has a storage modulus of ∼5.2 GPa at room temperature and ∼90 MPa in the rubbery state at 150 °C, 1 order of magnitude higher than those in previous reports. Nanopillars with diameters of ∼400 nm and an aspect ratio as high as ∼10 were printed by two-photon lithography. Experimentally, we observe shape recovery as collapsed and touching structures overcome stiction to stand back up. We develop a theoretical model to explain the recoverability of these sub-micrometer structures. Reconfigurable structural color prints with a resolution of 21150 dots per inch and holograms are demonstrated, indicating potential applications of the stiff shape memory polymers in high-resolution reconfigurable nanophotonics.

PurposeThis study examines the effect of audit quality on earnings management to beat earnings targets among Chinese listed firms, taking into account the firms’ corporate social responsibility (CSR) practice.Design/methodology/approachThe sample consists of all A-shares listed in the Chinese stock market from 2001 to 2019, except firms in the financial industry. Probit estimator is employed to observe the effect of audit quality, proxied by a binary variable indicating whether a firm is audited by a Big 4 audit firm, on the behavior of earnings management to beat earnings targets. Industry and year fixed effects are incorporated into the models to control for differences among industries and time periods.FindingsThe result of this study reveals that audit quality disciplines earnings management to beat earnings targets in Chinese firms. This result holds across different specification and endogeneity tests. The authors further find that auditors seem to be more tolerant to earnings-managed firms that actively disclose CSR activities. However, this moderating effect of CSR disclosure only exists among firms that manage earnings less aggressively.Practical implicationsThe findings of this study suggest that market participants should be mindful of the earnings management phenomenon and make their investment decisions after carefully dissecting and confirming the truthfulness of firms’ financial reporting. Regulators should raise the requirement on the capacity of auditing services to ensure the quality of the audit outcome.Originality/valueThis study is the first to investigate the effect of audit quality on earnings management to beat earnings targets in Chinese firms. Moreover, this study pioneers in observing the moderating effect of CSR disclosure on the relationship between audit quality and earnings management.

We examine the stock market performance of Vietnam’s listed firms in response to the country’s approval of the Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP). Employing an event study methodology, we first calculate the abnormal returns of all listed Vietnamese firms around the CPTPP’s approval date. Then, we attempt to link these abnormal returns to firms’ characteristics. We find evidence that the announcement of the CPTPP’s approval is associated with positive abnormal returns for Vietnam’s listed firms. We also find considerable heterogeneity in the magnitude and pace of the impacts of the CPTPP’s approval on market returns across Vietnam’s two stock exchanges. However, we fail to reject the null hypothesis that the market did not react to the CPTPP’s approval at the sectoral level.

Emerging immersive visual communication technologies require light sources with complex functionality for dynamic control of polarization, directivity, wavefront, spectrum, and intensity of light. Currently, this is mostly achieved by free space bulk optic elements, limiting the adoption of these technologies. Flat optics based on artificially structured metasurfaces that operate at the sub-wavelength scale are a viable solution, however their integration into electrically driven devices remains challenging. Here we demonstrate a radically new approach of monolithic integration of a dielectric metasurface into a perovskite light-emitting transistor. We show that nanogratings directly structured on top of the transistor channel yield an 8-fold increase of electroluminescence intensity and dynamic tunability of polarization. This new light-emitting metatransistor device concept opens unlimited opportunities for light management strategies based on metasurface design and integration. This article is protected by copyright. All rights reserved. Agency for Science, Technology and Research (A*STAR) Ministry of Education (MOE) Submitted/Accepted version This research was supported by the Agency for Science, Technology and Research A*STAR-AME programmatic grant on Nanoantenna Spatial Light Modulators for Next-Gen Display Technologies (Grant no. A18A7b0058) and the Singapore Ministry of Education MOE Tier 3 (Grant no. MOE2016-T3-1-006).

It has been long known that low molecular weight resists can achieve a very high resolution, theoretically close to the probe diameter of the electron beam lithography (EBL) system. Despite technological improvements in EBL systems, the advances in resists have lagged behind. Here we demonstrate that a low-molecular-mass single-source precursor resist (based on cadmium(II) ethylxanthate complexed with pyridine) is capable of a achieving resolution (4 nm) that closely matches the measured probe diameter (∼3.8 nm). Energetic electrons enable the top-down radiolysis of the resist, while they provide the energy to construct the functional material from the bottom-up─unit cell by unit cell. Since this occurs only within the volume of resist exposed to primary electrons, the minimum size of the patterned features is close to the beam diameter. We speculate that angstrom-scale patterning of functional materials is possible with single-source precursor resists using an aberration-corrected electron beam writer with a spot size of ∼1 Å.

Spin-dependent optical transitions are attractive for a plethora of applications in quantum technologies. Here we report on utilization of high quality ring resonators fabricated from TiO2 to enhance the emission from negatively charged boron vacancies (VB-) in hexagonal Boron Nitride. We show that the emission from these defects can efficiently couple into the whispering gallery modes of the ring resonators. Optically coupled VB- showed photoluminescence contrast in optically detected magnetic resonance signals from the hybrid coupled devices. Our results demonstrate a practical method for integration of spin defects in 2D materials with dielectric resonators which is a promising platform for quantum technologies.

Resonant metasurfaces provide a unique platform for enhancing multiwave nonlinear interactions. However, the difficulties over mode matching and material transparency place significant challenges in the enhancement of these multiwave processes. Here we demonstrate efficient nonlinear sum-frequency generation (SFG) in multiresonant GaP metasurfaces based on guided-wave bound-state in the continuum resonances. The excitation of the metasurface by two near-infrared input beams generates strong SFG in the visible spectrum with a conversion efficiency of 2.5 × 10–4 W–1, 2 orders of magnitude higher than the one reported in Mie-type resonant metasurfaces. In addition, we demonstrate the nontrivial polarization dependence on the SFG process. In contrast to harmonic generation, the SFG process is enhanced when using nonparallel polarized input-beams. Importantly, by varying the input pump beam polarization it is possible to direct the SFG emission to different diffraction orders, thereby opening up new opportunities for nonlinear light sources and infrared to visible light conversion.

Resonant metasurfaces are an attractive platform for enhancing the non-linear optical processes, such as second harmonic generation (SHG), since they can generate very large local electromagnetic fields while relaxing the phase-matching requirements. Here, we take this platform a step closer to the practical applications by demonstrating visible range, continuous wave (CW) SHG. We do so by combining the attractive material properties of gallium phosphide with engineered, high quality-factor photonic modes enabled by bound states in the continuum. For the optimum case, we obtain efficiencies around 5e-5 % W$^{-1}$ when the system is pumped at 1200 nm wavelength with CW intensities of 1 kW/cm$^2$. Moreover, we measure external efficiencies as high as 0.1 % W$^{-1}$ with pump intensities of only 10 MW/cm$^2$ for pulsed irradiation. This efficiency is higher than the values previously reported for dielectric metasurfaces, but achieved here with pump intensities that are two orders of magnitude lower.

In recent years, high-index dielectric nanoantennas supporting Mie resonances have emerged as a promising platform to create low-loss nanophotonic devices. The multipolar resonances naturally supported by this kind of nanoantennas allow designing systems in which the out-coupling radiation, and in particular the directivity, can be tailored at will. Moreover, unlike plasmonic counterparts, local electromagnetic fields in resonant dielectric nanoparticles concentrate inside the structures rather than outside. This allows enhancing light–matter interactions in their volume and boosting their linear and nonlinear optical properties by choosing suitable semiconductors as the material platform to build them. In this article, we will discuss recent results on active and tunable nanophotonics based on resonant dielectric and semiconductor nanostructures. Specifically, we will focus on two main topics: active tuning of dielectric nanoantennas and enhancement and spectral shaping of light emission using dielectric nanoantennas, including lasing. Finally, future research directions and proposed practical applications will also be discussed.

ms in Hanoi. Based on literature review and the results of some interviews, dependent variable of the motivation for accounting human resources by material stimulation includes seven attributes. The study has also performed some descriptive analysis, Cronbach's Alpha, Independent T-test and ANOVA for measuring the motivation for accounting human resources by material stimulation in the accounting service firms in Hanoi. The results show that the motivation for accounting human resources by material stimulation achieved an average of 3.74 and with Cronbach's Alpha coefficient greater than 0.6. The study does not find any difference on evaluation of the motivation for accounting human resources by material stimulation in terms of gender and job experience. Based on the findings, some recommendations are given for improving the motivation for accounting human resources by material stimulation in the accounting service firms in Hanoi.

This paper is conducted to investigate the impact levels of outside determinants on the quality of accounting human resources for sustainability of the accounting service firms in Hanoi. Data are collected using 145 questionnaires from accounting service firms. Based on the data collected, we use Cronbach’s Alpha, EFA and regression model for learning the effect of different variables on the quality of accounting human resources. The results show that three outside determinants including International integration of accounting, Policy of accounting human resource development and Accounting labor market needs had positive relationships with the quality of accounting human resources. Based on the findings, some recommendations are given for improving the quality of accounting human resources of accounting service firms in Hanoi to ensure sustainability, including applying international financial report standard (IFRS) in Vietnam, strengthening cooperation between universities and businesses, and improving the quality of the labor market.

We demonstrate highly efficient second harmonic generation from dielectric meta-surfaces based on gallium phosphide platform, utilizing quasi-bound-state-in-the-continuum resonances. In particular, we demonstrate an efficiency of 0.1 %/W using pulsed laser at an intensity of 10 MW/cm2 and 5e-5 %/W using continuous wave laser at an intensity of 1 kW/cm2.

Bound-states-in-the-continuum (BIC) is an emerging concept in nanophotonics with potential impact in applications, such as hyperspectral imaging, mirror-less lasing, and nonlinear harmonic generation. As true BIC modes are non-radiative, they cannot be excited by using propagating light to investigate their optical characteristics. In this paper, for the 1st time, we map out the strong near-field localization of the true BIC resonance on arrays of silicon nanoantennas, via electron energy loss spectroscopy with a sub-1-nm electron beam. By systematically breaking the designed antenna symmetry, emissive quasi-BIC resonances become visible. This gives a unique experimental tool to determine the coherent interaction length, which we show to require at least six neighboring antenna elements. More importantly, we demonstrate that quasi-BIC resonances are able to enhance localized light emission via the Purcell effect by at least 60 times, as compared to unpatterned silicon. This work is expected to enable practical applications of designed, ultra-compact BIC antennas such as for the controlled, localized excitation of quantum emitters., The optically inaccessible bound-states-in-the-continuum (BIC) is probed via sub-1-nm electron beam, where the cathodoluminescence emissions from Si nanoantenna arrays are able to reveal the coherent interaction length of quasi-BIC resonances.

To investigate the quantum confinement effect on excitons in hybrid perovskites, single-crystal platelets of CH3NH3PbBr3 are grown on mica substrates using one-step chemical vapor deposition. Photoluminescence measurements reveal a monotonous blue shift with a decreasing platelet thickness, which is accompanied by a significant increase in exciton binding energy from approximately 70 to 150 meV. Those phenomena can be attributed to the one-dimensional (1D) quantum confinement effect in the two-dimensional platelets. Furthermore, we develop an analytical model to quantitatively elucidate the 1D confinement effect in such quantum wells with asymmetric barriers. Our analysis indicates that the exciton Bohr radius of single-crystal CH3NH3PbBr3 is compressed from 4.0 nm for the thick (26.2 nm) platelets to 2.2 nm for the thin (5.9 nm) ones. The critical understanding of the 1D quantum confinement effect and the development of a general model to elucidate the exciton properties of asymmetric semiconductor quantum wells pave the way toward developing high-performance optoelectronic heterostructures.

A highly efficient nanocavity formed by optically coupled nanostructures is achieved by optimization of the collective Mie resonances in a one-dimensional array of semiconductor nanoparticles. Analysis of quasi-normal multipole modes enables us to reveal the close relation between the collective Mie resonances and Van Hove singularities. On the basis of these concepts, we experimentally demonstrate a directional GaAs nanolaser at cryogenic temperatures with well-defined, in-plane emission, which, moreover, can be controlled by selective excitation. The lasing threshold is shown to be significantly reduced by optimizing the interparticle gap such that the optimal near-field confinement is achieved at a resonant wavelength corresponding to the highest gain of GaAs. We show that the lasing performance of this nanolaser is orders of magnitude better than a nanowire-based laser of the same dimensions. The present work provides design guidelines for high performance in-plane emission nanolasers, which may find applications in future photonic integrated circuits.

7 pags., 4 figs., Solid-state room-temperature lasing with tunability in a wide range of wavelengths is desirable for many applications. To achieve this, besides an efficient gain material with a tunable emission wavelength, a high quality-factor optical cavity is essential. Here, we combine a film of colloidal CdSe/CdZnS core-shell nanoplatelets with square arrays of nanocylinders made of titanium dioxide to achieve optically pumped lasing at visible wavelengths and room temperature. The all-dielectric arrays support bound states in the continuum (BICs), which result from lattice-mediated Mie resonances and boast infinite quality factors in theory. In particular, we demonstrate lasing from a BIC that originates from out-of-plane magnetic dipoles oscillating in phase. By adjusting the diameter of the cylinders, we tune the lasing wavelength across the gain bandwidth of the nanoplatelets. The spectral tunability of both the cavity resonance and nanoplatelet gain, together with efficient light confinement in BICs, promises low-threshold lasing with wide selectivity in wavelengths., This work was supported by the A*STAR SERC Pharos programme (grant number 152 73 00025; Singapore). D.R.A. and J.A.S.-G. acknowledge support from the Spanish Ministerio de Ciencia e Innovacion (NANOTOPO FIS2017-91413-EXP, ́ MELODIA PGC2018-095777-B-C21, and a FPU Ph.D. Fellowship FPU15/03566, MCIU/AEI/FEDER, UE). H.V.D. gratefully acknowledges support from TUBA. The authors acknowledge Vytautas Valuckas (IMRE, A*STAR) for SEM characterization.

On-chip light sources are critical for the realization of fully integrated photonic circuitry. So far, semiconductor miniaturized lasers have been mainly limited to sizes on the order of a few microns. Further reduction of sizes is challenging fundamentally due to the associated radiative losses. While using plasmonic metals helps to reduce radiative losses and sizes, they also introduce Ohmic losses hindering real improvements. In this work, we show that, making use of quasi-bound states in the continuum, or supercavity modes, we circumvent these fundamental issues and realize the smallest purely semiconductor nanolaser thus far. Here, the nanolaser structure is based on a single semiconductor nanocylinder that intentionally takes advantage of the destructive interference between two supported optical modes, namely Fabry-Perot and Mie modes, to obtain a significant enhancement in the quality factor of the cavity. We experimentally demonstrate the concept and obtain optically pumped lasing action using GaAs at cryogenic temperatures. The optimal nanocylinder size is as small as 500 nm in diameter and only 330 nm in height with a lasing wavelength around 825 nm, corresponding to a size-to-wavelength ratio around 0.6. The obtained results pave the way for the development of smaller on-chip light sources free of Ohmic losses, which may find applications in the future photonic circuits., Comment: 29 pages, 9 figures

The improvement of light-emitting diodes (LEDs) is one of the major goals of optoelectronics and photonics research. While emission rate enhancement is certainly one of the targets, in this regard, for LED integration to complex photonic devices, one would require to have, additionally, precise control of the wavefront of the emitted light. Metasurfaces are spatial arrangements of engineered scatters that may enable this light manipulation capability with unprecedented resolution. Most of these devices, however, are only able to function properly under irradiation of light with a large spatial coherence, typically normally incident lasers. LEDs, on the other hand, have angularly broad, Lambertian-like emission patterns characterized by a low spatial coherence, which makes the integration of metasurface devices on LED architectures extremely challenging. A novel concept for metasurface integration on LED is proposed, using a cavity to increase the LED spatial coherence through an angular collimation. Due to the resonant character of the cavity, extending the spatial coherence of the emitted light does not come at the price of any reduction in the total emitted power. The experimental demonstration of the proposed concept is implemented on a GaP LED architecture including a hybrid metallic-Bragg cavity. By integrating a silicon metasurface on top we demonstrate two different functionalities of these compact devices: directional LED emission at a desired angle and LED emission of a vortex beam with an orbital angular momentum. The presented concept is general, being applicable to other incoherent light sources and enabling metasurfaces designed for plane waves to work with incoherent light emitters., 29 pages, 6 figures

We numerically and experimentally demonstrate that metasurfaces can be used to control the light emission from light emitting diodes (LED). This control provides a desired wavefront and functionality of the light emission in addition to enhancing light extraction efficiency. Simply placing the metasurface on top of the LED does not work as conventional metasurface designs require plane wave excitation, which LEDs cannot provide. To overcome this challenge we implement a novel concept using internal and external resonant cavities combined with the LED. Guided by our numerical simulations, we experimentally demonstrate this concept by fabricating Si and TiO2 metasurfaces on top of the resonant cavity LED structures. The integration of these metasurfaces with commercially available GaN and GaP LED devices show full wavefront control, beam deflection and beam collimation. Both the cavity and the metasurface enhance the LED radiation. Moreover, following the proposed principle, any random light emitting sources including fluorescent molecules and quantum dots can be integrated into a similar optical device to achieve focusing, beam deflecting, vortex beam generation and other capabilities.

Colloidal semiconductor nanoplatelets (NPLs) are highly promising luminescent materials owing to their exceptionally narrow emission spectra. While high-efficiency NPLs in non-polar organic media can be obtained readily, NPLs in aqueous media suffer from extremely low quantum yields (QYs), which completely undermines their potential, especially in biological applications. Here, we show high-efficiency water-soluble CdSe/CdS@Cd1−xZnxS core/crown@shell NPLs formed by layer-by-layer grown and composition-tuned gradient Cd1−xZnxS shells on CdSe/CdS core/crown seeds. Such control of shell composition with monolayer precision and effective peripheral crown passivation, together with the compact capping density of short 3-mercaptopropionic acid ligands, allow for QYs reaching 90% in water, accompanied by a significantly increased photoluminescence lifetime (∼35 ns), indicating the suppression of nonradiative channels in these NPLs. We also demonstrate the controlled attachment of these NPLs without stacking at the nanoscale by taking advantage of their 2D geometry and hydrophilicity. This is a significant step in achieving controlled assemblies and overcoming the stacking process, which otherwise undermines their film formation and performance in optoelectronic applications. Moreover, we show that the parallel orientation of such NPLs achieved by the controlled attachment enables directed emission perpendicular to the surface of the NPL films, which is highly advantageous for light extraction in light-emitting platforms. NRF (Natl Research Foundation, S’pore) ASTAR (Agency for Sci., Tech. and Research, S’pore) MOE (Min. of Education, S’pore) Accepted version

Optical irradiation with suitable energy can cool solids, a phenomenon known as optical refrigeration, first proposed in 1929 and experimentally achieved in ytterbium-doped glasses in 1995. Since then, considerable progress has been made in various rare earth element-doped materials, with a recent record of cooling to 91 K directly from ambient temperatures. For practical use and to suit future applications of optical refrigeration, the discovery of materials with facile and scalable synthesis and high cooling power density will be required. Herein we present the realization of a net cooling of 23.0 K in micrometre-thick 3D CH3NH3PbI3 (MAPbI3) and 58.7 K in exfoliated 2D (C6H5C2H4NH3)2PbI4 (PhEPbI4) perovskite crystals directly from room temperature. We found that the perovskite crystals exhibit strong photoluminescence upconversion and near unity external quantum efficiency, properties that are responsible for the realization of net laser cooling. Our findings indicate that solution-processed perovskite thin films may be a highly suitable candidate for constructing integrated optical cooler devices. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore)

High-index dielectric and semiconductor nanoparticles supporting strong electric and magnetic resonances have drawn significant attention in recent years. However, until now, there have been no experimental reports of lasing action from such nanostructures. Here, we demonstrate directional lasing, with a low threshold and high quality factor, in active dielectric nanoantenna arrays achieved through a leaky resonance excited in coupled gallium arsenide (GaAs) nanopillars. The leaky resonance is formed by partially breaking a bound state in the continuum generated by the collective, vertical electric dipole resonances excited in the nanopillars for subdiffractive arrays. We control the directionality of the emitted light while maintaining a high quality factor (Q = 2,750). The lasing directivity and wavelength can be tuned via the nanoantenna array geometry and by modifying the gain spectrum of GaAs with temperature. The obtained results provide guidelines for achieving surface-emitting laser devices based on active dielectric nanoantennas that are compact and highly transparent.

In the growing list of 2D semiconductors as potential successors to silicon in future devices, metal-halide perovskites have recently joined the family. Unlike other conversional 2D covalent semiconductors such as graphene, transition metal dichalcogenides, black phosphorus, etc., 2D perovskites are ionic materials, affording many distinct properties of their own, including high photoluminescence quantum efficiency, balanced large exciton binding energy and oscillator strength, and long carrier diffusion length. These unique properties make 2D perovskites potential candidates for optoelectronic and photonic devices such as solar cells, light-emitting diodes, photodetectors, nanolasers, waveguides, modulators, and so on, which represent a relatively new but exciting and rapidly expanding area of research. In this Review, the recent advances in emerging 2D metal-halide perovskites and their applications in the fields of optoelectronics and photonics are summarized and insights into the future direction of these fields are offered. NRF (Natl Research Foundation, S’pore) ASTAR (Agency for Sci., Tech. and Research, S’pore) MOE (Min. of Education, S’pore)

We report on the synthesis and optical gain properties of regularly shaped lead iodide (PbI2) platelets with thickness ranging from 10–500 nm synthesized by chemical vapor deposition methods. The as-prepared single crystalline platelets exhibit a near band edge emission of ∼500 nm. Whispering gallery mode (WGM) lasing from individual hexagonal shaped PbI2 platelets is demonstrated in the temperature-range of 77–210 K, where the lasing modes are supported by platelets as thin as 45 nm. The finite-difference time-domain simulation and the edge-length dependent threshold confirm the planar WGM lasing mechanism in such hexagonal shaped PbI2 platelet. Through a comprehensive study of power-dependent photoluminescence (PL) and time-resolved PL spectroscopy, we ascribe the WGM lasing to be biexcitonic in nature. Moreover, for different thicknesses of platelet, the lowest lasing threshold occurs in platelets of ∼120 nm, which attributes to the formation of a good Fabry–Pérot resonance cavity in the vertical direction between the top and bottom platelet surfaces that enhances the reflection. Our present study demonstrates the feasibility of planar light sources based on layered semiconductor materials and that their thickness-dependent threshold characteristic is beneficial for the optimization of layered material based optoelectronic devices. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore) Accepted version

Recently, organic-inorganic lead halide perovskites have gained great attention for their breakthrough in photovoltaic and optoelectronics. However, their thermal transport properties that affect the device lifetime and stability are still rarely explored. In this work, the thermal conductivity properties of single crystal CH

The different synthesis approaches and growth mechanisms of metal halide perovskites will be discussed along with their novel characteristics and applications., Nanomaterials refer to those with at least one dimension being at the nanoscale (i.e.

Recently, organic–inorganic lead halide perovskites have gained great attention for their breakthrough in photovoltaic and optoelectronics. However, their thermal transport properties that affect the device lifetime and stability are still rarely explored. In this work, the thermal conductivity properties of single crystal CH3NH3PbI3 platelets grown by chemical vapor deposition are studied via non-contact micro-photoluminescence (PL) spectroscopy. We developed a measurement methodology and derived expressions suitable for the thermal conductivity extraction for micro-sized perovskites. The room temperature thermal conductivity of ∼0.14 ± 0.02 W m−1 K−1 is extracted from the dependence of the PL peak energy on the excitation laser power. On changing the film thickness from 80 to 400 nm, the thermal conductivity does not show noticeable variations, indicating the minimal substrate effects due to the advantage of the suspended configuration. The ultra-low thermal conductivity of perovskites, especially thin films, suggests their promising applications for thermal isolation, such as thermal insulation and thermo-electricity. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore) Accepted version

Lead halide perovskites have recently become a rapidly growing research field due to their great potential in next‐generation solar cells and photonic sources. As a direct bandgap semiconductor, perovskites are also promising candidates for low‐threshold and multicolor lasing devices due to their high optical gain, ease of bandgap engineering, large absorption coefficient, and low defect state density. In particular, reduced‐dimensional perovskite structures including nanoplatelets, nanowires, and quantum dots, are crucial for the development of micro‐ or nanosized laser sources for optical chips and high‐resolution imaging, etc. Here, perovskite nanophotonics, in particular the lasing properties of perovskite nanostructures, are discussed. The rapid advances of small lasers based on perovskite nanostructures using both active and passive microcavities are reviewed; these are mainly classified into four sections: thin films, nanoplatelets, nanowires, and quantum dots. Lasing performance in terms of threshold, color‐tunability, spectral coherence, and stability is introduced from both materials and microcavity respects. Fundamental photophysical mechanisms involved in the photoluminescence lasing process, from absorption, emission to gain, are discussed in order to provide insightful understanding lasing properties of different types of perovskites. Finally, some future prospects for perovskite lasing devices are provided. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore) Accepted version