Concurrent Inhibition and Redistribution of Spontaneous Emission

Subscriber access provided by EDINBURGH UNIVERSITY LIBRARY | @ http://www.lib.ed.ac.uk

Letter

Concurrent Inhibition and Redistribution of Spontaneous Emission from All Inorganic Perovskite Photonic Crystals Songyan Hou, Aozhen Xie, Zhenwei Xie, Landobasa Y. M. Tobing, Jin Zhou, Liliana Tjahjana, Junhong Yu, Chathuranga Hettiarachchi, Dao Hua Zhang, Cuong Dang, Edwin Hang Tong Teo, Muhammad Danang Birowosuto, and Hong Wang ACS Photonics, Just Accepted Manuscript • DOI: 10.1021/acsphotonics.8b01655 • Publication Date (Web): 14 Mar 2019 Downloaded from http://pubs.acs.org on March 16, 2019

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Photonics

Concurrent Inhibition and Redistribution of Spontaneous Emission from All Inorganic Perovskite Photonic Crystals Songyan Hou†,‡, Aozhen Xie†,‡, Zhenwei Xie†,‡,¶, Landobasa Y. M. Tobing†, Jin Zhou†, Liliana Tjahjana†,‡, Junhong Yu†, Chathuranga Hettiarachchi†, Daohua Zhang†, Cuong Dang*,†,‡, Hang Tong Edwin Teo*,†,‡, Muhammad Danang Birowosuto*,†,‡ and Hong Wang*,†,‡ †School

of Electrical and Electronics Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 ‡CINTRA

(CNRS – International – NTU - THALES - Research Alliances / UMI 3288), 50 Nanyang Drive, Singapore 637553 ¶Nanophotonics

Research Centre, Shenzhen Key Laboratory of Micro-Scale Optical Information Technology, Shenzhen University, China 518060 E-mail: [email protected]; [email protected]; [email protected]; [email protected]

Abstract All inorganic cesium lead halide perovskite semiconductors exhibit great potential for nanolasers, light emitting diodes and solar cells due to their unique properties including low threshold, high quantum efficiency and low cost. However, the high material refractive index of perovskite semiconductors hinders light extraction efficiency for photonic and illumination applications. In this paper, we demonstrate high light extraction efficiency achieved in CsPbBr2.75I0.25 two dimensional photonic crystals. The perovskite photonic crystals exhibit both emission rate inhibition and light energy redistribution simultaneously. We observed 7.9 folds reduction of spontaneous emission rate with a slower decay in CsPbBr2.75I0.25 photonic crystals due to photonic bandgap effect (PBG). We also observed 23.5 folds of PL emission enhancement as a result of light energy redistribution from 2D guided modes to vertical direction in perovskite photonic crystals thin films, indicating a high intrinsic light extraction efficiency. Such a combination of inhibiting undesirable emission with redistributing light energy into useful modes offers a new promising approach in various applications for perovskite, including solar cell, displays and photovoltaics. Key words: perovskite, photonic crystals, light extraction efficiency, emission rate inhibition All inorganic halide perovskites possess a unique combination of intriguing properties in a broad range of optoelectronic devices, such as high carrier mobility, tunable emissions and economic cost for commercial use.1-3 Among these features, bright and tunable photoluminescence (PL) emissions and flexible fabrication methods highlight perovskite's potential in imaging, lasers, and even light emitting diodes(LEDs).4-11 However, the external collection efficiency of generated light is greatly hindered by the large internal reflection in perovskite thin films due to their high refractive index.12 Hence, most of the emitted light is coupled to in-plane guided modes in perovskites thin films, thereby serving as a fundamental limit for the light extraction efficiency in perovskite devices. Losses in LED and noises in lasers have been attributed to the uncoupled light

ACS Paragon Plus Environment

ACS Photonics 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

emission.13, 14 Therefore, increasing the extraction efficiency of useful modes while simultaneously inhibiting undesirable ones would make great improvements in perovskite devices. Although PL enhancement in perovskites has been widely demonstrated via increasing radiative rates, engineering perovskite nanocrystal size and interface doping,5, 15 improving extraction efficiency and inhibiting spontaneous emission rate of guided modes in perovskite have never been explored. Depositing a highly reflective metallic mirror at the backside enables high extraction efficiency in LEDs. In this case, the physical properties including lifetime and spontaneous recombination of emitters are directly manipulated by a surface plasmon cavity effect.16-18 The metallic layers increase internal quantum efficiencies with enhanced emission rate in semiconductors. However, the large absorption of metal limits their quantum efficiency enhancement. Recently, 2D photonic crystals have been utilized to improve optical performance of III-nitride LEDs and diamond layers.13, 14, 19, 20 2D photonic crystals have a periodic refractive index distribution which can control the propagation of light in the dielectric medium and enhance quantum efficiency with Purcell effect through the cavity.21-23 The photonic crystals can be well designed to tune its bandgap to spectrally overlap with that of the emission and penetrate through the whole device, eliminating 2D in-plane modes with PBG effect and thus extracting light emission out of plane with high collection efficiency.24-28 However, inhibition of spontaneous light emission and redistribution of light energy with high extraction efficiency in perovskites photonic crystals have yet to be demonstrated. Electron beam lithography (EBL) is a high-performance nanolithography system with large area writing capability. It also allows the adaptation of the system configuration to specific application requirements along with high resolution. Compared with patterning perovskite using focus ion beam (FIB) with foreign ions into films29 and nanoimprinting with slow speed and stamp fabrication30, 31, EBL is clean while it is also flexible in designing of any pattern with high resolution. In the future, we will make the stamp (by EBL) and use it in nanoimprinting for mass production. In this paper, we design and fabricate photonic crystals directly on CsPbBr2.75I0.25 perovskite thin films by electron beam lithography and reactive ion etching (RIE). The photonic crystals structure exhibit strong light emission enhancement with a factor of 23.5 while their light emission rate is largely suppressed by 7.9 folds compared to the unpatterned area in the same sample. According to three-dimensional finite-difference time-domain (3D FDTD) simulations, the PL enhancement is attributed to the redistribution of light energy where most of in-plane spontaneous emission of guided modes are inhibited due to photonic crystals PBG effect, leading to the increase of extraction efficiency via out-of-plane modes. In addition, we also observed PL peak shifts from CsPbBr2.75I0.25 perovskite photonic crystals with different lattice constants.


Page 2 of 17

Page 3 of 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Photonics

Figure 1: Characterization of spin-cast CsPbBr2.75I0.25 perovskite thin film on SiO2/Si substrate. (a) Optical microscope image of CsPbBr2.75I0.25 thin film on SiO2/Si substrate. (b) AFM scanning image. The arithmetic average surface roughness is 15.0 nm. (c) Normalized absorption (dotted line) and PL spectra (solid line) of CsPbBr2.75I0.25 (red) and CsPbBr3 (blue) thin films. The hybrid CsPbBr2.75I0.25 perovskite thin film was spin cast on SiO2/Si substrate with DMSO as host solvent (see Methods for full details). The CsPbBr3 thin film is already known as a base in ultra-bright and highly efficient inorganic based perovskite light-emitting diodes with32 or without nanostructures33. The as-prepared CsPbBr2.75I0.25 thin film presents smooth surface with a roughness of 15 nm with a thickness of 150 nm (Figure 1 and Supporting Information Figure S1), indicative of a good quality thin film. A rough surface will benefit a high light extraction efficiency34, 35, while the roughness can increase the difficulty of EBL processing. Here we choose perovskite film with 15 nm roughness as a trade-off between external quantum efficiency and photonic crystals fabrication. And no Fabry-Perot cavity was observed under this roughness in transmission spectra (see Supporting Information Figure S2). The CsPbBr2.75I0.25 is chosen due to its larger Stokes shift than that of CsPbBr3, which enables the inhibition of self-absorption and simplifies photonic crystals design. Figure 1c shows UV-Vis absorption and emission spectra of em CsPbBr2.75I0.25 and CsPbBr3. The maximum emissions ( max ) occur at 549 nm and 525 nm, and absorption transition edges appear at 526 nm and 520 nm for CsPbBr2.75I0.25 and CsPbBr3,


ACS Photonics 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

em respectively. The longer max and absorption edge of CsPbBr2.75I0.25 result from phase transition

due to the iodine dopant, which is consistent with those in literature.36-38

Figure 2: The perovskite photonic crystals design and theoretical analyses of PBG effects. (a) Schematic of perovskite photonic crystals. (b) SEM image of a perovskite 2D photonic crystals. Inset: top view of calculated electric field distributions in 2D photonic crystals at a/λ = 0.53. Scale bar: 200 nm. (c) Photonic band structure of 2D hexagonal lattice photonic crystals calculated using FDTD. (d) Calculation of spontaneous light emission rate for various frequency, normalized by unpatterned structure. (e) Calculated light extraction efficiency in the vertical direction as a function of frequency, normalized by unpatterned structure. (f) Calculated cross-sectional (x-z) electric field distributions, illustrating how light is redistributed by photonic crystals. The lattice constant 280 nm and air hole diameter 180 nm are used for the simulation. The thickness of perovskite is 150 nm. Spontaneous light emission is usually manipulated by optical modes and photonic crystals offer an effective platform to control optical modes.39, 40 The perovskite photonic crystals were achieved using EBL and RIE techniques(Figure 2a and b). This fabrication is challenging as the perovskite materials are usually unstable as they are hygroscopic. However, here we chose all inorganic


Page 4 of 17

Page 5 of 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Photonics

perovskite materials with the improvement in humidity stability.41 Compared to focused ion beam lithography,42 we are able to make much larger structures with faster speed with EBL. The optical modes inside perovskite photonic crystals film can be categorized into two modes. First are guided modes, which confine light emission into perovskite thin films due to the high refractive index. Second are vertical modes, which can penetrate perovskite films and increase extraction efficiency. Generated spontaneous light emission can be coupled into both guided modes and vertical modes, and only the vertical modes contribute to useful energy while guided modes cause losses and noises. Thus, the total spontaneous emission rate (  total ) can be expressed by:13

 total   guided   vertical

( 1)

where  guided and  vertical are the generated light emission rate for guided modes and vertical modes, respectively. For unpatterned perovskite films surrounded by air, emission is strongly confined inside perovskite films (𝛾𝑔𝑢𝑖𝑑𝑒𝑑 ≫ 𝛾𝑣𝑒𝑟𝑡𝑖𝑐𝑎𝑙), leading to low extraction efficiency. However, when emission frequency is overlapped with PBG in an incorporated 2D photonic crystals, guided modes in films can be greatly inhibited with slower emission rate and most of emitted light emission is then redistributed into vertical modes with higher extraction efficiency. This implies that both reduction of spontaneous emission rate in guided modes and redistribution of light energy can appear simultaneously in photonic crystals. To further investigate light emission inhibition and energy redistribution in perovskite photonic crystals, 3D FDTD simulations are carried out to calculate spontaneous emission rate and light extraction efficiency, and the results are normalized with values from simulated unpatterned perovskite thin films. The details of calculation can be found in Supporting Information. Figure 2c illustrates the photonic bandgap structure of 2D photonic crystals. Figure 2d shows that the light emission rate within photonic bandgap is decreased by around 16.7 times compared to that of unpatterned area. Meanwhile, light extraction efficiency within bandgap region is largely increased by around 32.0 folds (Figure 2e), which results from the redistribution of light emission. Cross-sectional views of electric field distributions are shown in Figure 2f), revealing how light is controlled by PBG effect in photonic crystals. Obviously, for emission wavelengths lying outside of photonic bandgap region, the light extraction efficiencies are much lower, indicating light emission is mostly confined inside guided in-plane modes. However, when the frequency overlaps with bandgap region, the emission rate of guided modes is greatly reduced (𝛾𝑔𝑢𝑖𝑑𝑒𝑑 ∼ 0) and emission energy is largely emitted out at vertical direction.


ACS Photonics 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Figure 3: Optical measurements of perovskite photonic crystals. (a) and (c): Steady state PL and time resolved PL spectrum from perovskite photonic crystals with lattice constants of 256 nm, 260 nm, 274 nm, 282 nm and without pattern, respectively., which are pumped by a focused laser beam with a diameter of ~1 µm. Inset of (a) shows photographic image from a sample with three different lattice constants photonic crystals excited by an unfocused laser with a diameter around 100 µm. Scale bar: 20 µm. (b) Polarization measurements of emission from photonic crystals (black) and excitation (red). (d) PL intensity enhancement (red spheres) and emission rate inhibition (blue spheres) in perovskite photonic crystals, respectively. In order to optimize the quality of perovskite photonic crystals, we exposed perovskite film to various electron dose during EBL processing (see Supporting Information Figure S3) and found the best quality of photonic crystals occurred under the dose around 1100 µC/cm2, and a minimum effect of electron on perovskite along with complete exposure was achieved under this dose (see Supporting Information Figure S4). To quantify the performance of perovskite photonic crystals, detailed optical measurements were conducted on photonic crystals films with various lattice constants. As shown in Figure 3a, perovskite photonic crystals demonstrated higher PL intensity than that from unpatterned area. The PL intensity is greatly enhanced up to 23.5 folds in perovskite photonic crystals with a lattice constant of 282 nm compared to that of unpatterned area at the same pump energy density. Photonic crystals rectangular areas exhibit brighter emissions when excited with an unfocused laser (inset of Figure 3a), which further proves the PL intensity enhancement. This enhancement is solely related to the extraction efficiency improvement as we did not observe lasing when we excited with different powers (see Supporting Information Figure S5). Notably, we also found


Page 6 of 17

Page 7 of 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Photonics

small PL peaks shifted to shorter wavelengths from 550 nm in unpatterned perovskite to around 520 nm in photonic crystals areas. These shifts are attributed to the PBG effect in photonic bandgap structure and qualitatively agrees with the expectation from FDTD simulations (Figure 2a). This kind of band edge effect contributes to unpolarized light emissions of photonic crystals samples even when excited with a polarized laser (Figure 3b). Figure 3c presents intensity-dependent PL decays fitted with three exponential functions for both perovskite photonic crystals and unpatterned samples. The relevant key parameters are listed in Supporting Information Table S1. Clearly, the perovskite photonic crystals exhibit much slower decays compared to unpatterned films: 20.97 ns and 2.66 ns, respectively (see Supporting Information Table S1). The slower decays in perovskite photonic crystals are due to the inhibition of light emission at guided modes, resulting in the increase of lifetime. And the redistribution of light energy into vertical modes contribute the enhancement of PL intensity. These results are in good agreement with the simulation in Figure 2 and both light emission inhibition and redistribution are experimentally realized as shown in Figure 3d. For comparison, we also summarized the performance of various light emitters with photonic crystals structures in Table 1. PL intensity enhancement and simultaneously inhibition of emission rate are found only in several limited photonic crystals. However, perovskite photonic crystals in this work demonstrates hitherto at visible region the highest PL intensity enhancement with high inhibition of spontaneous emission rate among all light emitters with 2D photonic crystals structures. Table 1: Summary of performance of light emitters with 2D photonic crystals structures

Diamond PhC19 GaInAsP PhC13 GaN PhC43 GaAs PhC44 SiO2/SiNx PhC45 Silicon PhC46 Perovskite PhC (this work)

Maximum PL Intensity Enhancement 6 5 3.5 1.5 500 23.5

Maximum Emission Rate Inhibition 5 70 7.9

Wavelength Red NIR Blue NIR Green NIR Green

In conclusion, we have successfully fabricated perovskite photonic crystals with EBL and RIE techniques and observed strong light redistribution with inhibition concurrently. Compared to unpatterned perovskite films, the light spontaneous emission rate of perovskite photonic crystals is greatly inhibited by 7.9 folds due to photonic bandgap effect, and simultaneously PL intensity is largely enhanced by a factor of 23.5 implying high extraction efficiency. Those values are still in the same order as those calculated by 3D FDTD simulations considering the errors from the fabrications and the optical constants used in the simulation (calculated PL intensity enhancement and emission rate inhibition are 16.7 and 32.0 folds, respectively). Both experiments and simulation further prove light inhibition and energy redistribution from perovskite photonic crystals thin films. In addition, we believe our perovskite photonic crystals structures open up a new possibility for solar cell of different perovskite materials47, as the photonic crystals can not


ACS Photonics 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

only brighten the devices, but also increase light absorption at bandgap region as a back side reflector48, which in turn can improve the performance of solar cells.47

Methods CsPbBr2.75I0.25 Thin Film Fabrication: CsPbBr2.75I0.25 solution was prepared by dissolving CsBr, CsI and PbBr2 with a molar ratio of 0.75:0.25:1 in DMSO (0.5 M) and stirred at 100 ℃ till complete dissolution. CsPbBr2.75I0.25 thin film was prepared by spin-cast precursor solution on SiO2/Si wafer at 4000 rpm (acceleration: 1000 rpm/s) for the 30 s and blow- drying by N2 in the last 15 s when sample was spinning,49 giving a thickness around 150 nm. The thin film was then annealed at 100 ℃ on hotplate for 15 min. The CsPbBrxI3-x is relatively stable with the humidity and the sample can sustain of about one week in the open air49. The lithography process was performed in the vacuum condition while we kept our samples in the vacuum desiccator directly after the fabrication. The measurement was performed at the same day. Perovskite Photonic Crystal Fabrication: The perovskite thin film was spin coated with 200 nm electron sensitive 950 PMMA polymer and baked at 180 ℃ for 3 mins. Then, the PMMA polymer was exposed to electron beam writing (Raith EBPG5000) with 100 keV voltage and 1 nA beam current and developed in MIBK/IPA. The nanopatterns were then transferred into perovskite thin film by reactive ion etching (RIE Oxford Plasmalab80 System) with a gas mixture of SF6 and Ar at 170 W forward power. Optical Characterization: Absorption spectra of perovskite thin films were obtained using UVVIS spectrometer (Shimadzu UV-2450), while the PL and lifetime measurements were carried out using free space home-built micro-PL setup at ambient environment at room temperature. A 355 nm pulse laser (VisUV, PicoQuant) with 15 ps linewidth and 10 MHz repetition rate was focused on samples with a microscope objective (Olympus 40x, NA = 0.65, focused laser beam diameter, ~ 1 µm). PL signal was collected by a Peltiercooled photomultiplier tube (Hamamatsu H7422 series) coupled with a grating spectrometer (Edinburgh Instruments F900 and Bentham TMS300) and the PL image was collected by a silicon charge coupled device (CCD). Time resolved PL measurement was performed using a time-correlated single-photon counting acquisition module (Micro Photon Devices MPD series) at selected peak wavelengths with a bandwidth of 20 nm. Surface Characterization: LEO 1550 Gemini field emission scanning electron microscopy (FESEM) was used to obtain SEM images and the roughness of perovskite thin film was investigated by Bruker Dimension Edge Atomic Force Microscope. Theoretical Simulations Numerical simulations were carried out using 3D finite difference time domain (FDTD) method (Lumerical Inc). The photonic bandgap is calculated using the band structure analysis group in FDTD while the light extraction efficiency is simulated using quantum efficiency analysis group. The hexagonal lattice of holes with radius = 90 nm were etched into the whole perovskite layer. The lattice constant is 280 nm and the thickness of perovskite was set as 150 nm. A dipole cloud analysis group was used to excite the photonic crystals structure. The boundary conditions were set as Bloch, Bloch and PML for x, y and z, respectively. The maximum and the minimum mesh steps are 10 and 0.25 nm, respectively. The final photonic band structure was plotted by sweeping


Page 8 of 17

Page 9 of 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Photonics

the parameters: K-Gamma, M-K and Gamma-M. For the extraction analysis, we used FDTD solutions’ Far field projection functions to calculate the far field angular distribution. Once we finished in sweeping the parameters, we analyzed the far field results averaged over all dipole orientations and locations. In this case, we calculated the ratio between the patterned and unpatterned samples for the power transmitted into a 20° cone normal to the surface. For the emission rate analysis, we calculated from the ratio for the dipole power. The optical constants of CsPbBr2.75I0.25 perovskite thin films are obtained from spectroscopic ellipsometer and their detailed values are shown in Supporting Information Figure S6.

Acknowledgements The authors acknowledge financial supports from the Ministry of Education (MOE2016-T2-1-052 and MOE2017-T1-002-142) and National Research Foundation of Singapore (NRFCRP12-201304). Z. Xie also acknowledge the support of the National Natural Science Foundation of China (Grant No. 11604218).

Supporting Information Available The Supporting Information is available free of charge on the ACS Publications website.

References 1. Green, M. A.; Ho-Baillie, A.; Snaith, H. J., The emergence of perovskite solar cells. Nature photonics 2014, 8 (7), 506. 2. Tan, Z.-K.; Moghaddam, R. S.; Lai, M. L.; Docampo, P.; Higler, R.; Deschler, F.; Price, M.; Sadhanala, A.; Pazos, L. M.; Credgington, D., Bright light-emitting diodes based on organometal halide perovskite. Nat. Nanotechnol. 2014, 9 (9), 687-692. 3. Frost, J. M.; Butler, K. T.; Brivio, F.; Hendon, C. H.; Van Schilfgaarde, M.; Walsh, A., Atomistic origins of high-performance in hybrid halide perovskite solar cells. Nano letters 2014, 14 (5), 2584-2590. 4. Noh, J. H.; Im, S. H.; Heo, J. H.; Mandal, T. N.; Seok, S. I., Chemical management for colorful, efficient, and stable inorganic–organic hybrid nanostructured solar cells. Nano letters 2013, 13 (4), 1764-1769. 5. Zhang, X.; Lin, H.; Huang, H.; Reckmeier, C.; Zhang, Y.; Choy, W. C.; Rogach, A. L., Enhancing the brightness of cesium lead halide perovskite nanocrystal based green light-emitting devices through the interface engineering with perfluorinated ionomer. Nano letters 2016, 16 (2), 1415-1420. 6. Kumawat, N. K.; Dey, A.; Narasimhan, K.; Kabra, D., Near infrared to visible electroluminescent diodes based on organometallic halide perovskites: structural and optical investigation. ACS photonics 2015, 2 (3), 349-354. 7. Li, G.; Tan, Z.-K.; Di, D.; Lai, M. L.; Jiang, L.; Lim, J. H.-W.; Friend, R. H.; Greenham, N. C., Efficient light-emitting diodes based on nanocrystalline perovskite in a dielectric polymer matrix. Nano letters 2015, 15 (4), 2640-2644. 8. Hou, S.; Birowosuto, M. D.; Umar, S.; Anicet, M. A.; Tay, R. Y.; Coquet, P.; Tay, B. K.; Wang, H.; Teo, E. H. T., Localized emission from laser-irradiated defects in 2D hexagonal boron nitride. 2D Materials 2017, 5 (1), 015010. 9. Timpu, F.; Sergeyev, A.; Hendricks, N. R.; Grange, R., Second-harmonic enhancement with Mie resonances in perovskite nanoparticles. Acs Photonics 2016, 4 (1), 76-84.


ACS Photonics 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

10. Chen, S.; Roh, K.; Lee, J.; Chong, W. K.; Lu, Y.; Mathews, N.; Sum, T. C.; Nurmikko, A., A photonic crystal laser from solution based organo-lead iodide perovskite thin films. Acs Nano 2016, 10 (4), 3959-3967. 11. Xing, G.; Mathews, N.; Lim, S. S.; Yantara, N.; Liu, X.; Sabba, D.; Grätzel, M.; Mhaisalkar, S.; Sum, T. C., Low-temperature solution-processed wavelength-tunable perovskites for lasing. Nat. Mater. 2014, 13 (5), 476. 12. Das, S.; Yang, B.; Gu, G.; Joshi, P. C.; Ivanov, I. N.; Rouleau, C. M.; Aytug, T.; Geohegan, D. B.; Xiao, K., High-performance flexible perovskite solar cells by using a combination of ultrasonic spray-coating and low thermal budget photonic curing. Acs Photonics 2015, 2 (6), 680-686. 13. Fujita, M.; Takahashi, S.; Tanaka, Y.; Asano, T.; Noda, S., Simultaneous inhibition and redistribution of spontaneous light emission in photonic crystals. Science 2005, 308 (5726), 12961298. 14. Wierer Jr, J. J.; David, A.; Megens, M. M., III-nitride photonic-crystal light-emitting diodes with high extraction efficiency. Nature Photonics 2009, 3 (3), 163. 15. Tian, Y.; Merdasa, A.; Unger, E.; Abdellah, M.; Zheng, K.; McKibbin, S.; Mikkelsen, A.; Pullerits, T. n.; Yartsev, A.; Sundström, V., Enhanced organo-metal halide perovskite photoluminescence from nanosized defect-free crystallites and emitting sites. The Journal of Physical Chemistry Letters 2015, 6 (20), 4171-4177. 16. Lee, Y.-J.; Kim, S.-H.; Huh, J.; Kim, G.-H.; Lee, Y.-H.; Cho, S.-H.; Kim, Y.-C.; Do, Y. R., A high-extraction-efficiency nanopatterned organic light-emitting diode. Appl. Phys. Lett. 2003, 82 (21), 3779-3781. 17. Shen, Y. C.; Wierer, J. J.; Krames, M. R.; Ludowise, M. J.; Misra, M. S.; Ahmed, F.; Kim, A. Y.; Mueller, G. O.; Bhat, J. C.; Stockman, S. A., Optical cavity effects in InGaN/GaN quantum-well-heterostructure flip-chip light-emitting diodes. Appl. Phys. Lett. 2003, 82 (14), 2221-2223. 18. Okamoto, K.; Niki, I.; Shvartser, A.; Narukawa, Y.; Mukai, T.; Scherer, A., Surfaceplasmon-enhanced light emitters based on InGaN quantum wells. Nat. Mater. 2004, 3 (9), 601. 19. Ondič, L. s.; Dohnalová, K. i.; Ledinský, M.; Kromka, A.; Babchenko, O.; Rezek, B., Effective extraction of photoluminescence from a diamond layer with a photonic crystal. ACS nano 2010, 5 (1), 346-350. 20. Wiesmann, C.; Bergenek, K.; Linder, N.; Schwarz, U. T., Photonic crystal LEDs– designing light extraction. Laser & Photonics Reviews 2009, 3 (3), 262-286. 21. Purcell, E. M., Spontaneous emission probabilities at radio frequencies. In Confined Electrons and Photons, Springer: 1995; pp 839-839. 22. Lodahl, P.; Van Driel, A. F.; Nikolaev, I. S.; Irman, A.; Overgaag, K.; Vanmaekelbergh, D.; Vos, W. L., Controlling the dynamics of spontaneous emission from quantum dots by photonic crystals. Nature 2004, 430 (7000), 654. 23. Englund, D.; Fattal, D.; Waks, E.; Solomon, G.; Zhang, B.; Nakaoka, T.; Arakawa, Y.; Yamamoto, Y.; Vučković, J., Controlling the spontaneous emission rate of single quantum dots in a two-dimensional photonic crystal. Physical review letters 2005, 95 (1), 013904. 24. Yablonovitch, E., Inhibited spontaneous emission in solid-state physics and electronics. Physical review letters 1987, 58 (20), 2059. 25. Fan, S.; Villeneuve, P. R.; Joannopoulos, J.; Schubert, E., High extraction efficiency of spontaneous emission from slabs of photonic crystals. Physical review letters 1997, 78 (17), 3294.


Page 10 of 17

Page 11 of 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Photonics

26. Tian, Y.; Zhou, C.; Worku, M.; Wang, X.; Ling, Y.; Gao, H.; Zhou, Y.; Miao, Y.; Guan, J.; Ma, B., Highly Efficient Spectrally Stable Red Perovskite Light ‐ Emitting Diodes. Advanced Materials 2018, 30 (20), 1707093. 27. Makarov, S. V.; Milichko, V.; Ushakova, E. V.; Omelyanovich, M.; Cerdan Pasaran, A.; Haroldson, R.; Balachandran, B.; Wang, H.; Hu, W.; Kivshar, Y. S., Multifold emission enhancement in nanoimprinted hybrid perovskite metasurfaces. ACS Photonics 2017, 4 (4), 728735. 28. Schünemann, S.; Brittman, S.; Chen, K.; Garnett, E. C.; Tüysüz, H., Halide Perovskite 3D Photonic Crystals for Distributed Feedback Lasers. ACS Photonics 2017, 4 (10), 2522-2528. 29. Gholipour, B.; Adamo, G.; Cortecchia, D.; Krishnamoorthy, H. N. S.; Birowosuto, M. D.; Zheludev, N. I.; Soci, C., Organometallic Perovskite Metasurfaces. 2017, 29 (9), 1604268. 30. Wang, H.; Haroldson, R.; Balachandran, B.; Zakhidov, A.; Sohal, S.; Chan, J. Y.; Zakhidov, A.; Hu, W., Nanoimprinted Perovskite Nanograting Photodetector with Improved Efficiency. ACS Nano 2016, 10 (12), 10921-10928. 31. Pourdavoud, N.; Wang, S.; Mayer, A.; Hu, T.; Chen, Y.; Marianovich, A.; Kowalsky, W.; Heiderhoff, R.; Scheer, H.-C.; Riedl, T., Photonic Nanostructures Patterned by Thermal Nanoimprint Directly into Organo-Metal Halide Perovskites. 2017, 29 (12), 1605003. 32. Zhang, L.; Yang, X.; Jiang, Q.; Wang, P.; Yin, Z.; Zhang, X.; Tan, H.; Yang, Y.; Wei, M.; Sutherland, B. R.; Sargent, E. H.; You, J., Ultra-bright and highly efficient inorganic based perovskite light-emitting diodes. Nature Communications 2017, 8, 15640. 33. Lin, K.; Xing, J.; Quan, L. N.; de Arquer, F. P. G.; Gong, X.; Lu, J.; Xie, L.; Zhao, W.; Zhang, D.; Yan, C.; Li, W.; Liu, X.; Lu, Y.; Kirman, J.; Sargent, E. H.; Xiong, Q.; Wei, Z., Perovskite light-emitting diodes with external quantum efficiency exceeding 20 per cent. Nature 2018, 562 (7726), 245-248. 34. Wierer Jr, J. J.; David, A.; Megens, M. M., III-nitride photonic-crystal light-emitting diodes with high extraction efficiency. Nature Photonics 2009, 3, 163. 35. Cao, Y.; Wang, N.; Tian, H.; Guo, J.; Wei, Y.; Chen, H.; Miao, Y.; Zou, W.; Pan, K.; He, Y.; Cao, H.; Ke, Y.; Xu, M.; Wang, Y.; Yang, M.; Du, K.; Fu, Z.; Kong, D.; Dai, D.; Jin, Y.; Li, G.; Li, H.; Peng, Q.; Wang, J.; Huang, W., Perovskite light-emitting diodes based on spontaneously formed submicrometre-scale structures. Nature 2018, 562 (7726), 249-253. 36. Zhao, X.; Ng, J. D. A.; Friend, R. H.; Tan, Z.-K., Opportunities and Challenges in Perovskite Light-Emitting Devices. ACS Photonics 2018, 5 (10), 3866-3875. 37. Huang, C.-Y.; Zou, C.; Mao, C.; Corp, K. L.; Yao, Y.-C.; Lee, Y.-J.; Schlenker, C. W.; Jen, A. K.; Lin, L. Y., CsPbBr3 perovskite quantum dot vertical cavity lasers with low threshold and high stability. ACS Photonics 2017, 4 (9), 2281-2289. 38. Chen, S.; Nurmikko, A., Stable Green Perovskite Vertical-Cavity Surface-Emitting Lasers on Rigid and Flexible Substrates. ACS Photonics 2017, 4 (10), 2486-2494. 39. Zhang, Z.; Zhang, L.; Hedhili, M. N.; Zhang, H.; Wang, P., Plasmonic gold nanocrystals coupled with photonic crystal seamlessly on TiO2 nanotube photoelectrodes for efficient visible light photoelectrochemical water splitting. Nano letters 2012, 13 (1), 14-20. 40. Kempa, K.; Kimball, B.; Rybczynski, J.; Huang, Z.; Wu, P.; Steeves, D.; Sennett, M.; Giersig, M.; Rao, D.; Carnahan, D., Photonic crystals based on periodic arrays of aligned carbon nanotubes. Nano Letters 2003, 3 (1), 13-18. 41. Liu, D.; Yang, C.; Bates, M.; Lunt, R. R., Room-Temperature Processing of Inorganic Perovskite Films to Enable Flexible Solar Cells. arXiv preprint arXiv:1806.06855 2018.


ACS Photonics 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

42. Gholipour, B.; Adamo, G.; Cortecchia, D.; Krishnamoorthy, H. N.; Birowosuto, M. D.; Zheludev, N. I.; Soci, C., Organometallic perovskite metasurfaces. Advanced Materials 2017, 29 (9), 1604268. 43. McGroddy, K.; David, A.; Matioli, E.; Iza, M.; Nakamura, S.; DenBaars, S.; Speck, J.; Weisbuch, C.; Hu, E., Directional emission control and increased light extraction in GaN photonic crystal light emitting diodes. Appl. Phys. Lett. 2008, 93 (10), 103502. 44. Wang, Q.; Stobbe, S.; Lodahl, P., Mapping the local density of optical states of a photonic crystal with single quantum dots. Physical review letters 2011, 107 (16), 167404. 45. Do, Y. R.; Kim, Y. C.; Song, Y. W.; Cho, C. O.; Jeon, H.; Lee, Y. J.; Kim, S. H.; Lee, Y. H., Enhanced light extraction from organic light‐emitting Diodes with 2D SiO2/SiNx photonic crystals. Advanced Materials 2003, 15 (14), 1214-1218. 46. Mahdavi, A.; Sarau, G.; Xavier, J.; Paraïso, T. K.; Christiansen, S.; Vollmer, F., Maximizing photoluminescence extraction in silicon photonic crystal slabs. Scientific reports 2016, 6, 25135. 47. Vynck, K.; Burresi, M.; Riboli, F.; Wiersma, D. S., Photon management in twodimensional disordered media. Nat. Mater. 2012, 11 (12), 1017. 48. Chutinan, A.; Kherani, N. P.; Zukotynski, S., High-efficiency photonic crystal solar cell architecture. Opt. Express 2009, 17 (11), 8871-8878. 49. Ng, Y. F.; Jamaludin, N. F.; Yantara, N.; Li, M.; Irukuvarjula, V. K. R.; Demir, H. V.; Sum, T. C.; Mhaisalkar, S.; Mathews, N., Rapid Crystallization of All-Inorganic CsPbBr3 Perovskite for High-Brightness Light-Emitting Diodes. ACS Omega 2017, 2 (6), 2757-2764.


Page 12 of 17

Page 13 of 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Photonics

Graphical TOC Entry Perovskite semiconductors exhibit excellent properties suitable for nanolaser, light emitting diode and solar cells, yet their collection efficiency has been greatly limited by light confinement inside perovskite due to its high refractive index. We proposed to solve this problem by inhibiting spontaneous emission rate at guided modes and redistribute light energy into vertical modes simultaneously via the photonic bandgap effect in perovskite photonic crystals, where 23.5-fold photoluminescence intensity enhancement and 7.9-fold reduction of emission rate have been demonstrated.


ACS Photonics 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Perovskite semiconductors exhibit excellent properties suitable for nanolaser, light emitting diode and solar cells, yet their collection efficiency has been greatly limited by light confinement inside perovskite due to its high refractive index. We proposed to solve this problem by inhibiting spontaneous emission rate at guided modes and redistribute light energy into vertical modes simultaneously via the photonic bandgap effect in perovskite photonic crystals, where 23.5-fold photoluminescence intensity enhancement and 7.9-fold reduction of emission rate have been demonstrated.


Page 14 of 17

Page 15 of 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Photonics

Figure 1: Characterization of spin-cast CsPbBr2.75I0.25 perovskite thin film on SiO2/Si substrate. (a) Optical microscope image of CsPbBr2.75I0.25 thin film on SiO2/Si substrate. (b) AFM scanning image. The arithmetic average surface roughness is 15.0 nm. (c) Normalized absorption (dotted line) and PL spectra (solid line) of CsPbBr2.75I0.25 (red) and CsPbBr3 (blue) thin films.


ACS Photonics 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Figure 2: The perovskite photonic crystals design and theoretical analyses of PBG effects. (a) Schematic of perovskite photonic crystals. (b) SEM image of a perovskite 2D photonic crystals. Inset: top view of calculated electric field distributions in 2D photonic crystals at a/λ = 0.53. Scale bar: 200 nm. (c) Photonic band structure of 2D hexagonal lattice photonic crystals calculated using FDTD. (d) Calculation of spontaneous light emission rate for various frequency, normalized by unpatterned structure. (e) Calculated light extraction efficiency in the vertical direction as a function of frequency, normalized by unpatterned structure. (f) Calculated cross-sectional (x-z) electric field distributions, illustrating how light is redistributed by photonic crystals. The lattice constant 280 nm and air hole diameter 180 nm are used for the simulation. The thickness of perovskite is 150 nm.


Page 16 of 17

Page 17 of 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Photonics

Figure 3: Optical measurements of perovskite photonic crystals. (a) and (c): Steady state PL and time resolved PL spectrum from perovskite photonic crystals with lattice constants of 256 nm, 260 nm, 274 nm, 282 nm and without pattern, respectively., which are pumped by a focused laser beam with a diameter of ~1 µm. Inset of (a) shows photographic image from a sample with three different lattice constants photonic crystals excited by an unfocused laser with a diameter around 100 µm. Scale bar: 20 µm. (b) Polarization measurements of emission from photonic crystals (black) and excitation (red). (d) PL intensity enhancement (red spheres) and emission rate inhibition (blue spheres) in perovskite photonic crystals, respectively.


Concurrent Inhibition and Redistribution of Spontaneous Emission

Recommend Documents