Resonantly Enhanced White-Light Emission Involving Energy and

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C: Plasmonics; Optical, Magnetic, and Hybrid Materials

Resonantly Enhanced White-Light Emission Involving Energy and Charge Transfer in One-Dimensional Hybrid Material: (ABT)[PbBr] 2

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Amira Samet, Smail Triki, and Younes Abid J. Phys. Chem. C, Just Accepted Manuscript • DOI: 10.1021/acs.jpcc.9b00361 • Publication Date (Web): 13 Feb 2019 Downloaded from http://pubs.acs.org on February 14, 2019

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The Journal of Physical Chemistry

Resonantly Enhanced White-Light Emission Involving Energy and Charge Transfer in One-Dimensional Hybrid Material: (ABT)2[Pbbr3] Amira Samet*a, Smail Trikib and Younes Abida aLaboratoire bUniv

de Physique appliquée, Université de Sfax, B. P. 1171, 3000 Sfax, Tunisia.

Brest, CNRS, CEMCA, 6 Avenue Le Gorgeu C. S. 93837-29238, Brest Cedex3, France.

Abstract This work focus on the white light emission process occurring in a new organic-inorganic hybrid metal halide material, whith formula (C7H12N2S)2[PbBr3] abbreviated as (ABT)2[PbBr3]. Its structure consists on one-dimensional PbBr3 twin chains surrounded by 2aminobenzothiazole (ABT) organic cations. The introduction of the optically active organic ligand (ABT) into the organic inorganic hybrid (OIH) material leads to original optical properties; indeed, under UV irradiation this material shows a white light emission with an impressive intensity that can be seen even with naked eye. Pholuminescence (PL) spectrum is characterized by a large emission band covering a wide range of the visible spectrum and composed by bleu, green, yellow and red components around 450 nm, 475 nm, 530 nm and 580 nm respectively. The PL measurements with vaious excitations shows that white light emission occurs only in a norrow resonant excitation range around 3.14 eV (394nm). PLE investigation and DFT band structure calculation revealed that this resonant excitation range corresponds to the coincidence of an intrinsec distribution of self trapet states in the inorganic PbBr3 distorted chain, with the frontier molecular orbitals of the organic cation. In addition, such an interaction between two ionic chromophores placed at very close distances is beleaved to be accompanied by a Dexter charge / energy transfert.

Introduction The title compound belongs to the large family of hybrid organic metal – halide with the general formula (R-NH3)nMmXp, where X is a halide (Cl,Br, I), M is a metal and R is protonated amine. Their structures are built up from MX6 octahedra sharing corners, edges or faces forming naturally zero, one, two or three dimensional networks in conjunction with organic units.1-8 The staking of inorganic and organic components at the molecular scale gives the opportunity to design original hybrid materials and therefor to obtain tunable physical properties.9,10 During the three last decades these materials have attracted the attention of physicists and chemists for their optoelectronic properties and their potential interest for technological applications such as field-effect transistors and light emitting diodes (LED).11,12 Recently, the (3D) organic– inorganic lead halides CH3NH3PbX3 have been successfully employed as absorber in photovoltaic solar cells giving rise to a consistent and rapid progress which has risen dramatically from 3.8% to over 22% in less than five years.13–15 The two-dimensional (2D)

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layered structures, have also been explored extensively. They usually show narrow photoluminescence band, holding a great promise in advanced optoelectronics.16,17 More recently, a subclass of hydrids has recently attracted attention for their broad emission band and white-light emission with full width at half maximum (FWHM) up to 180-200 nm.18 This property is promising in the field of solid lighting devices. Indeed, compared to the usual white light emitter phosphorous, a hybrid material acts as a unique illuminant entity rather than a mixture, and provides a homogeneous and uniform white light emission.19 The first white light emitting organic metal halide was discovered 4 years ago,18 and so far only few works have been published. Indeed, the most interesting are based on lead bromide while the process of emission of white light is not well known, however in all works the authors considered that the emission process is mainly related to self-trapped excitons owing to distortions within the metal halide network.18,20-23 It should be noted that in all the lead bromides studied copmpounds, the organic molecules are optically inactive and no resonant transfert of energy has been evidenced. In order to investigate the interaction between organic and inorganic components and in hoping the tuning and the enhancement of the optical properties, a comprehensive systematic study was conducted in our laboratory, consisting in introducing optically active organic molecules into these materials.24, 25 In this context, we report the study of a new organic inorganic hybrid material based on lead bromide and containing a luminescent organic molecule aminobenzothiazolium (ATB). The structure of (ABT)2[PbBr3]consists of particular edge sharing octahedral lead bromide chains exhibiting a remarkable distorsion and surrounded by aminobenzothiazolium cations. We will show that this distortion generates an intrinsic distribution of trapet states in perfect coincidence and resonance with the molecular frontier orbitals of organic cations, all of these states overlap in a narrow band of energy inside the gap (around 3.14 eV). Strikingly, white light emission occurs only under resonant excitation whith these levels. Based on the PL of the organic ammonium salt, the Photoluminescence excitation (PLE) and the time-resolved PL, it will be shown that the broadband luminescence has dual origin: one from diammonium-related molecular fluorescence around 450 nm and 475 nm and another from self-trapped excitons (STE) around 530 nm and 580 nm. Experimental results will be confirmed by density functional theory (DFT) calculations.

2. Experimental section 2.1. Crystal synthesis and thin film preparation The organic-inorganic hybrid compound (ABT)2[PbBr3]was prepared in stoichiometric condition by dissolving PbBr2 and 2-aminobenzothiazole (ABT) in an aqueous HBr solution (37%). The mixture was stirred and kept at room temperature for several weeks. After slow evaporation, transparent crystals were obtained. Thin films of (ABT)2[PbBr3]were prepared by spin coating on glass slides 1.5 ml of a water solution in which 20 mg of the crystallized title compound has been dissolved. The films were then annealed at 100 ◦C for some minutes to remove residual solvent.

2.2. Single crystal X-ray diffraction A single crystal of good quality was selected for diffraction experiments. The data were collected on a BruKer AXS CCD area detector system equipped with monochromatic MoKα radiation (0.71073 A) at 293(2) K. The crystal structure was solved by direct method using SHELXS-97.26 Successive refinements based on F2 leads to a reliability factors of R = 0.0388. The crystal structure was solved and refined in the monoclinic system (space group P21/n). Crystal data and structure refinements details are reported in Table 1.


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Table 1. Crystallographic data for (ABT)2[PbBr3]. Formula Temperature (K) Crystal system/Space group a (Å) b (Å) c (Å) α(°) β(°) γ(°) V (Å3) Z Refinementmethod Programs system Rint

(C7H7N2S)2[PbBr3] 293 (2) Triclinic/P 21/n 11.9097(5) 4.4191(2) 24.2484(10) 90.00 94.332(4) 90.00 1272.55 2 Full-matrix least-squares on F2 SHELXL 97 and SHELXS 97 0.0388

2.3. Optical measurements The photoluminescence spectra were recorded using a JOBIN YVON HR 320 spectrometer with an excitation wavelength of 375 nm line of a laser. The sample temperature was controlled using a helium closed cycle cryostat. Optical absorption spectrum of the spin coated film was deduced from direct transmission measurements performed using a conventional UV–Vis spectrophotometer (HITACHI, U-3300). Photoluminescence excitation (PLE) was recorded on a Fluoromax-4 spectro-fluorimeter equipped with a xenon lamp as excitation source.

2.4. Electronic band structure calculations. Our calculations are performed with the modified Becke and Johnson (mBJ)27 exchange potential in the framework of full-potentiallinearizedaugmented plane wave (FP-LAWP) method as implemented in the Wien2k package.28 RMT’s are chosen in such a way that there was no charge leakage from the core and therefore total energy convergence was ensured. For wave function in the interstitial region the plane wave cut-off value of Kmax=3/RMT was taken. Convergence was checked through self-consistency. The convergence was ensured for less than 0.01 mRyd/a.u.

3. Results and discussion 3.1. Structure description The present compound crystallizes in the monoclinic P21/n space group with two formula units in unit cell (Z = 2). The cell dimensions are: a = 11.9097(5) Å, b=4.4191(2) Å, c = 24.2484(10) Å and β = 94.332(4)°. As can be seen from the packing diagram of Figure.1, the structure consists of infinite double-chain framework along the b axis constructed through inorganic PbBr6 octahedra. Each Pb atom is coordinated by six Br atoms, including three triple-bridged Br atoms (Br2), two double-bridged Br atoms (Br3), and one terminal Br atom (Br1). Obviously the configuration of the PbBr6 octahedron is rather distorted, as deduced from the discrepancy of Pb−Br bond lengths (2.846 Å to 3.195 Å) and bond angles (84.56° to 93.44°).



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Figure 1. (a) Packing diagram of the (ABT)2[PbBr3] compound viewed along the b-axis, (b) the PbBr infinite double chain structure and (c) atom numbering scheme for the (ABT) organic cation, the hydrogen bonds are shown as dashed lines.

The magnitude of distortion of the octahedron (Δd) is quantitatively measured by the following equation: 1

∆𝑑 = 6∑

𝑑𝑖 ― 𝑑 2

( ) 𝑑

(1)

Where di is the individual Pb–Br bond lengths and d is the average Pb–Br bond length. As a result, Δd is calculated to be 1.188×10−3, which can be comparable with those reported corrugated 2D and distorted 1D hybrids18,29,30 meaning that the PbBr6 octahedron in the title compound is quite distorted. As a result, such distorted octahedrons will in favour of the exciton self-trapping.31,32 Organic 2-aminobenzothiazole (ATB) cations are boned to the 1D infinite PbBr3 semiconducting wires through N−H···Br hydrogen bonds. As seen in figure 1(b and c), only Br1 and Br3 are involved in the hydrogen bonds wherein N1-H…Br1= 3.39Å and N1H…Br3= 3.36 Å; while Br2 is shut in the inorganic chains. We will see below that a such dissymmetric distortion and strong N-H..Br connection are in correlation with the original optical properties of the material namely the competition of STE states and energy /charge transfer process.


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3.2. Density of state calcutation As we will show later, because of the chemical composition of the material and the coexistence of two organic and inorganic components, the assignement of the bands and the unambiguous analysis of the emission and absorption spectra is not easy. For such systems, the calculation of the band structure and the determination of the electronic density of state provides a powerful tool to draw up an energy diagram, to analyze the optical spectra and to distinguish between the contribution of the different components in the emission processes. In this context we have performed a simulation of the electronic density of states in terms of Density Functional Theory (DFT). The calculated electronic band structure along the high symmetry points of the Brillouin zone of (ABT)2[PbBr3] hybrid compound as well as of solely inorganic and organic sublattices are illustrated in Figure 2.

Figure 2 . Calculated electronic band structures of (a) the (ABT) organic cation (b) infinite inorganic chains PbBr3 and (c) the organic-inorganic hybrid material (ABT)2[PbBr3], the new band appearing in electronic band structure of the hybrid compound suggests the energy/ charge transfer mechanism. The comparision reveals the appearance of new electronic states in the below-gap region within the band structure of the hybrid compound. The results which are obtained by the semi-local mBJ method are in perfect agreement with those of the experimental data as will be seen below. Indeed the mBJ exchange potential, allows the calculation of band gaps with accuracy similar to the very expensive Green function (GW) calculations.27 It is a local approximation to an atomic ‘‘exact-exchange’’ potential and a screening term. Therefore, the mBJ method has the capability to overcome the well-known shortcoming of the DFT-based methods in predicting the bandgaps. Partial density of states (PDOS) of the hybrid compound is plotted in Figure 3.



Figure 3. (a) Partial dendity of states (DOS) of lead and bromine atoms in the (ABT)2[PbBr3] compound and the corresponding l-decomposed DOS of like-states s and p. (b) contribution of p-orbital of carbon, nitrogen and sulfer atoms in the (ABT)2[PbBr3] compound.(c) The intensity of luminescence signal under various excitations. The dashed gray box illustrates the resonant excitation spectral range in which white light emission occurs. It is obvious that the valence band maximum is composed primarily of the inorganic module, namely Pb 6s and Br 4p atomic orbitals while the conduction band minimum is made up of an admixture of inorganic (Pb 6s and Br 4p) as well as organic (C 2p, N 2p and S 3p) atomic orbitals. These results show that the organic (ABT) ligand have a direct contributions to the electronic states around the Fermi level, on contrary to similar coupounds based on non conjugate organic ligands in which the inorganic part mainly contributes to the band gap.33 Indeed the energy levels alignment of the (ABT) π-conjugated cation with those of the quasilinear wires of PbBr3 may be critical for an enhancement of carrier mobility in the hybrid structure. Moreover, a sharp subband below the conduction band is noted around 3.3 eV. Obviously, new property due to strong interaction between organic and inorganic entities arises in the hybrid with a functional organic cation. It originates from the superposition/ resonance of the organic (C1 2p, N2 2p and S 3p) thiazole ring atomic orbitals and the inorganic (Pb 6p and Br1 4p) ones, see fig 3(a,b). It is worthy to note that this band accurately fits the experimentally OA band at 370 nm (3.35eV) as will be seen below. Such, theoretical calculations predict resonance energy/charge transfer.


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3.3 Optical study So far, optically inactive and saturated organic molecules have been used in hybrid organic metal-halide materials, where they play solely the role of insulator barriers with a low dielectric constant and a large band gap. As we employed here a luminescent molecule containing π conjugated electrons, we have performed photoluminescence and UV-Vis absorption measurements on thin films of the (ABT)2[PbBr3] hybrid compound as well as of the (ABT.Br) organic salt, for comparison. As seen in Figure (4A-a) and (4A-a’); UV Vis absorption spectrum of both films exhibit high energy absorption bands around 300 nm, while no exciton absorption band is detected for the organic cation (ABT) nor for the inorganic PbBr3 chains. Further, the tauc plot methode lead to a band gap of about 370nm (3,35 eV) for the (ABT)2[PbBr3] hybrid compound in well agreement whith theoretical DFT calculation.

Figure 4 : (A) (a,a’) OA spectrum ; (b,b’) PL spectra excited at 375 nm and (c,c’)PLE spectrum of (ABT)2[PbBr3] hybrid compound and

(ABT.Br) salt. (B) Images of

(ABT)2[PbBr3] crystal under ambient light and 375 nm irradiation. (C) Commission Internationale de l’Eclairage (CIE) chromaticity coordinates of (ABT)2[PbBr3]. As mentiond above, upon excitation arround 375 nm, studied crystals show an unusual photoluminescence spectrum including multiple emission peaks with main maxima at 450 nm, 475nm, 530 nm , and a shoulder at 580 nm, spanning a wide range of the visible light (see fig (4 A-b). The CIE chromaticity coordinates of the title compound calculated from its PL spectra are ploted in figure 4C. Indeed as shown in figure 4B crystal of (ABT)2[PbBr3]exibits bright



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whigt appearance upon UV irradiation. In order to investigate the contribution of organic and inorganic components in the emission spectrum, we have measured the PL spectra of the ABT.Br salt, the latter exhibit a band at 435 nm and a shoulder at 470 nm ;see fig (4A-b’). The comparison between these PL spectra shows that the blue and green components at 450 nm and 475 nm, in photoluminescence spectra of the (ABT)2[PbBr3]hybrid compound, originate from π-π*transitions whithin the (ABT) organic cation. Their red shift may be due to the crystal staking of the aromatic rings of the cation. Whereas the yellow and orange components at 530 nm and 580 nm are related to the lead bromide PbBr3 chains and their strong interaction with the organic cation. Indeed these bands are far removed from the band edge what denotes strongly bound excitonic state, which is suggested to originate from STE attributed to lattice deformation.33 Let us recall that the first white light emitting materials were revealed by Dohner and all in 2014,18,34 afterwards, many studies were reported on materials belonging to the same family of materials and having a competitive efficiency of emission of the white light.21,30,31 In table 2 we have summarized their main optical characteristics. Table 2. Comparative table of structural and optical properties of lead bromide based OIH materials at room temperature: Compound

PL emission

FWHM

Ex. Abs Dimensionality

(C4N2H14)PbBr4 30

475 nm

157 nm

375 nm

1D

(HMTA)3Pb2Br7 35

560 nm

158 nm

-

1D

(C6H14N)PbBr 36

630 nm

220 nm

375 nm

1D

(ABT)2[PbBr3]

450 nm, 475nm

(Present work)

530 nm and 580nm

210 nm

394nm

1D

(EDBE) PbBr4 18

573 nm

215 nm

371 nm

2D

(C6H11NH3)2PbBr4 21

620 nm

660 meV

389 nm

2D

α-(DMEN) PbBr4 29

510 nm

180 nm

-

2D

These materials have several common features, namely, optically inactive organic molecules and highly distorted lead halide lattices. The emission of broad band of white or quasi- white light has been associated with radiative recombinations of the self- trapped excitons in the elastically-deformed PbBr6 octahedra. In our case, the PbBr3 chain is distorted and the organic cation is luminescent, which has given a wider emission band with many components associated with the π-π*transitions whithin the organic cation in the blue green region in one hand and the self trapped exciton in the orange region on the other hand. The split of the latter in two components (530 nm and 580 nm) may be related to the strong interaction between organic and inorganic entities through inequivalent N-H Br1 and N-H-Br3 hydrogen bonds. To further confirm that the self trapped excitons are behind the orange emission (530 nm and 580 nm) in the luminescence of the OIH compound rather than triplet (ABT) organic cation states or permanent lattice defects, time-resolved PL spectroscopy was measured on (ABT)2[PbBr3] single crystals when excited at 375 nm. Adequate filters were used to follow the time evolution of each component of the PL spectrum. The intensity–time curves are presented in figure 5. They are fitted using an exponential function I(t) = I0 × exp−(t/τ)}, where τ and I0 are two fitting parameters.37,38


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Figure 5 : PL decay of (ABT)2[PbBr3]after 375 nm photoexcitation measured at room temperature. For a comparative study we have collected in table 3, the characteristics of the self-trapped excitons (STEs) of the previously investigated PbBr based white light emitter materials, whose have different dimensionalities and connectivity modes. Compared with the free and the triplet organic excitons which have generally life times of picco second and hundreds of nano seconds order of magnitudes respectively, 39,40 we can see that the common feature of these materials is the order of magnitude of STEs life time which is of a few ns. For our material the Yellow and Orange components have almost the same life times with an average of ( = 2ns), a fact that reflects, on the one hand, the pivotal contribution of the STEs in the mechanism of emission, on the other hand, their coupling with the electronic * transitions within the organic cation via the Dexter charge transfer under the resonant excitation. Table 3: Comparative table of structural and STE emission decay of some white-light emitting lead bromide based OIH materials at room temperature: Formula (C6H16N2 )3Pb2Br10 41

Dimensionality 1D

Connectivity

PL emission

τ (ns)

mode

(nm)

corner- and

585

23.03

edge-sharing (C6H16N2 )PbBr4 41

2D

corner-sharing

596

2.7

(C5H14N2 )2Pb3Br1041

2D

corner- and

564

3.6

edge-sharing (C7H16N)PbBr341

1D

face-sharing

674

4.3

(ABT)2[PbBr3]

1D

corner- and

450

2.06

edge-sharing

475

1.3

530

1.27

580

1.17

C4N2H14PbBr4 30

1D

475

37.3

(EDBE)[PbBr4]18

2D

573

14



For a better understanding of the mechanisms involved in the emission process we have also carried out photoluminescence measurements under different excitations covering a wide range of the UV-visible spectrum. As seen in figure 6, a systematic study of the intensities of the different lines of luminescnces reveals, surprinsingly and intrestingly, that white light emission is showed only for a fairly narrow excitation range around 394 nm (3.14 eV), aligned perfectly with the measured PLE band; see figure (4A-c).

Figure 6: The photoluminescence spectra of (ABT)2[PbBr3] under various excitations, showing the resonant excitation spectral range around 394 nm in which white light emission occurs. Out of this excitation interval no white light emission is observed. Furthermore, this excitation band coincides impeccably with the hybrid sp levels of the Pb-Br bond and the frontier (C, N and S) orbitals of the organic cation (as seen in fig 3). In other words, white light emission is observed only for resonant excitations with intrinsic electronic levels corresponding to frontier molecular orbitals of the organic cation and coinciding also with the inorganic PbBr3 orbitals. Moreover, in such system, the interaction of two excited ionic chromophores placed in close proximity may lead to an emission process involving Forster/Dexter resonant energy transfer (FRET).42 Let us recall that FRET is a non radiative mechanism describing the transfer of energy or charges between two chromophores: A donor molecule (D) having a large band gap to an acceptor molecul (A) having a smaller band gap. The unique characteristics of FRET have been effectively exploited in optoelectronic devices43,44 and biomedical diagnostics.45,46 During last decades FRET has been widely studied


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in system containing semiconductor quantum dots QD, interacting with organic dyes,47,48 because QDs have the advantage to have regulated luminescence in wide range by tuning their sizes. Whereas only few work were reported on FRET in hybrid perovskites and their derivatives. The first study that revealed FRET in hybrid perovskites and their derivatives was done by Papavassiliou49 and Ema and all,50 20 years ago. Just recently, and as part of a systematic and comprehensive study that we undertook in our lab, we reported two works in which we have demonstrated that FRET can be the origine of the emission of white light in a hybrid material in which both organic and inorganic components are luminescent.24,25 The transfer process is efficient when the two chromophores are placed in close proximity interaction distance, and when the emission spectra of the donor overlaps significantly the absorption spectra of the acceptor. In the case of (ABT)2[PbBr3], the two criterium are quite satisfied. In fact XRD measurements have shown that PbBr3 chains are linked with (ABT) organic cation through N-H...Br bonds of 3.3 A° of length, which is in favor for Dexter charge transfer. In addition, as shown in figure 4(d); PLE measurements on the organic salt reveald a large absorption signal that overlaps entirely the the PLE spectra of the hybrid compound (fig (4A-c) and (4A-c’)), further more as described above the DFT density of states calculation confirms this results and demonstrates a coincidence of the electronic levels of the hybrid PbBr bond whith those of organic cation, a fact which infavor the energy and charge transfert between the anionique chain (PbBr3)- and the cation (ABT)+.

Conclusion In summary, in this work we have synthesized a new one-dimensional hybrid material based on lead bromide and a carefully chosen chromophore organic cation. Such a mixture led to an original 1D structure in which electronic oraganic levels interact resonantely whith the self trapped excitonic states of the distorted PbBr6 octahedra. This resonant excitation has been well characterized by optical spectroscopy measurements and DFT density of states calculations. Under resonant excitations with these electronic states this material shows an impressive white light emission. Out of this resonant spectral range, no significant luminescence is shown. We believe that this rather original behavior in the family of hybrid metal halides, turns this material into a potential candidate for optoelectronic applications, and makes this work a substantial contribution to a better understanding of the macanisms involved in the white light emission processes.

References (1) Vincent, B.R.; Robertson, K.V.; Cameron, T.S.; O. Knop, O.; Can. Alkylammonium lead halides. Part 1. Isolated PbI64− ions in (CH3NH3)4PbI6•2H2O. J. Chem. 1987, 65, 1042-1046 (2) Wang, S.; Mitzi, D.B.; Field, C.A.; Guloy, A. Synthesis and Characterization of [NH2C(I):NH2]3MI5 (M = Sn, Pb): Stereochemical Activity in Divalent Tin and Lead Halides Containing Single Perovskite Sheets. J. Am. Chem. Soc. 1995, 117, 5297-5302. (3) Calabrese, J.; Jones, N.L.; Harlow, R.L.; Herron, N.; Thorn, D.L.; Wang, Y. Preparation and characterization of layered lead halide compounds. J. Am. Chem. Soc. 1991, 113, 23282330. (4) Tanaka, K.; Takahashi, T.; Ban, T.; Kondo, T.; Uchida, K.; Miura, N. Comparative study on the excitons in lead-halide-based perovskite-type crystals CH3NH3PbBr3 CH3NH3PbI3. Solid State Commun. 2003, 127, 619-623. (5) Dammak, T.; Elleuch, S.; Bougzhala, H.; Mlayah, A.; Chtourou, R.; Abid,Y. Synthesis, vibrational and optical properties of a new three layered organic–inorganic perovskite (C4H9NH3)4Pb3I4Br6 . J. Luminescence. 2009, 129, 893-897.



(6) Elleuch, S.; Abid, Y.; Mlayah, A.; Boughzala, H. Vibrational and optical properties of a one‐dimensional organic–inorganic crystal [C6H14N]PbI3. J. Raman Spectrosc. 2008, 39, 786– 792. (7) Samet, A.; Ben ahmed, A.; Mlayah, A.; Boughzala, H.; Hlil, E.K.; Abid, Y. Optical properties and ab initio study on the hybrid organic inorganic material [(CH3)2NH2]3[BiI6]. J. Mol. Struct. 2010, 977, 72-77. (8) Samet, A.; Boughzala, H.; Khemakhem, H.; Abid, Y. Synthesis, characterization and nonlinear optical properties of Tetrakis(dimethylammonium) Bromide Hexabromobismuthate: {[(CH3)2NH2]+}4·Br−·[BiBr6]3− . J. Mol. Struct. 2010, 984, 23-29. (9) Mitzi, D.B. Synthesis, Crystal Structure, and Optical and Thermal Properties of (C4H9NH3)2MI4 (M = Ge, Sn, Pb). Chem. Mater. 1996, 8 (3), 791–800. (10) Sekine, T.; Okuno, T.; Awaga, K. Observation of Spontaneous Magnetization in the Layered Perovskite Ferromagnet, (p-Chloroanilinium)2CuBr4 . Inorg. Chem. 1998, 37 (9), 2129–2133. (11) Mitzi, D.B.; Dimitrakopoulos, C.D. Hybrid Field‐Effect Transistor Based on a Low‐Temperature Melt‐Processed Channel Layer. Adv. Mater. 2002, 14, 1772 -1776. (12) Schimizu, M.; Ishihara, T. Subpicosecond transmission change in semiconductor– embedded photonic crystal slab: Toward ultrafast optical switching. Appl. Phys. Lett. 2002, 80 (16), 2836-2838. (13) Jeon, N. J.; Noh, J.H.; Yang, W. S.; Kim, Y. C.; Ryu, S.; Seo, J.; Seok, S. Compositional engineering of perovskite materials for high-performance solar cells. Nature. 2015, 517, 476480. (14) Kojima, A.; Teshima, K.; Shirai, Y.; Miyasaka, T. Organometal Halide Perovskites as Visible-Light Sensitizers for Photovoltaic Cells. J. Am. Chem. Soc. 2009, 131 (17), 6050–6051. (15) Yang, W. S.; Park, B.-W.; Jung, E. H.; Jeon, N. J.; Kim, Y. C.; Lee, D. U.; Shin, S. S.; Seo, J.; Kim, E. K.; Noh, J. H.; et al. Iodide Management in Formamidinium-Lead- Halide– Based Perovskite Layers for Efficient Solar Cells. Science. 2017, 356 (6345), 1376–1379. (16) Lanty, G.; Zhang, S.; Lauret, J. S.; Deleporte, E.; Audebert, P.; Bouchoule, S.; Lafosse, X.; Zuñiga-Pérez, J.; Semond, F.; Lagarde, D.; Médard, F.; Leymarie. Hybrid cavity polaritons in a ZnO-perovskite microcavity. Phys. Rev. B. 2011, 84, 195449:1-5. (17) Deschler, F.; Price, M.; Pathak, S.; Klintberg, L. E.; Jarausch, D.-D.; Higler, R.; Hüttner, S.; Leijtens, T.; Stranks, S. D.; Snaith, H. J.; Atatüre, M.; Phillips, R. T.; Friend, R. H. High Photoluminescence Efficiency and Optically Pumped Lasing in Solution-Processed Mixed Halide Perovskite Semiconductors. J. Phys. Chem. Lett. 2014, 5(8), 1421-1426. (18) Dohner, E. R.; Jaffe, A.; Bradshaw, L. R.; Karunadasa, H. I. Intrinsic White-Light Emission from Layered Hybrid Perovskites. J. Am. Chem. Soc. 2014, 136, 13154-13157. (19) Tan, Z. K.; Moghaddam, R. S.; Lai, M. L.; Docampo, P.; Higler, R.; Deschler, F.; Price, M.; Sadhanala, A.; Pazos, L. M.; Credgington, D.; Hanusch, F.; Bein, T.; Snaith, H. J.; Friend. R. H. Bright light-emitting diodes based on organometal halide perovskite. Nat. Nanotechnol. 2014, 9, 687-692. (20) Dohner, E. R.; Hoke, E. T.; Karunadasa, H. I. Self-Assembly of Broadband White-Light Emitters. J. Am. Chem. Soc. 2014, 136, 1718-1721. (21) Yangui, A.; Garrot, D.; Lauret, J. S.; Lusson, A.; Bouchez, G.; Deleporte, E.; Pillet, S.; Bendeif, E. E.; Castro, M.; Triki, S. et al. Optical Investigation of Broadband White-Light Emission in Self-Assembled Organic-Inorganic Perovskite (C6H11NH3)2PbBr4. J. Phys. Chem. C. 2015, 119, 23638-23647. (22) Hu, T.; Smith, M. D.; Dohner, E. R.; Sher, M. J.; Wu, X. X.; Trinh, M. T.; Fisher, A.; Corbett, J.; Zhu, X. Y.; Karunadasa, H. I. et al. Mechanism for Broadband White-Light


Page 12 of 15

Page 13 of 15 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 from Two-Dimensional (110) Hybrid Perovskites. J. Phys. Chem. Lett. 2016, 7, 22582263. (23) Cortecchia, D.; Yin, J.; Bruno, A.; Lo, S.-Z. A.; Gurzadyan, G. G.; Mhaisalkar, S.; Bredas, J.-L.; Soci, C. Polaron Self-Localization in White-Light Emitting Hybrid Perovskites. J. Mater. Chem. C. 2017, 5(11), 2771-2780. (24) Dammak, T.; Abid, Y. Quasi-White Light Emission Involving Forster Resonance Energy Transfer in a New Organic Inorganic Tin Chloride Based Material (AMPS)[SnCl6]. Opt. Mater. (Amst). 2017, 66, 302–307. (25) Barkaoui, H.; Abid, H.; Yangui, A.;Triki, S.; Boukheddaden, K.; Abid,Y. Yellowish White-Light Emission Involving Resonant Energy Transfer in a New One-Dimensional Hybrid Material: (C9H10N2)PbCl4. J. Phys. Chem. C, 2018, 122 (42), 24253–24261. (26) Sheldrick GM (1997) SHELXL-97, Program for Crystal Structure Refinement, University of Göttingen (Germany 1997). (27) Tran, F.; Blaha, P. Accurate Band Gaps of Semiconductors and Insulators with a Semilocal Exchange-Correlation Potential. Phys. Rev. Lett. 2009, 102, 226401: 1-4. (28) Blaha, P.; Schwarz, K.; Madsen, G.K.H.; Kvasnicka, D.; Luitz, J. WIEN2K: An Augmented Plane Wave and Local Orbitals Program for Calculating Crystal Properties, edited by K. Schwarz, Vienna University of Technology, Austria, 2001. (29) Mao, L.; Wu, Y.; Stoumpos, C. C.; Wasielewski M. R.; Kanatzidis, M. G. White-Light Emission and Structural Distortion in New Corrugated Two-Dimensional Lead Bromide Perovskites. J. Am. Chem. Soc. 2017, 14, 5210−5215. (30) Yuan, Z.; Zhou, C.; Tian, Y.; Shu, Y.; Messier, J.; Wang, J. C.; Van de Burgt, L. J.; Kountouriotis, K.; Xin, Y.; Holt, E.; Schanze, K.; Clark, R.; Siegrist T.; Ma, B. Onedimensional organic lead halide perovskites with efficient bluish white-light emission. Nat. Commun. 2017, 8, 14051: 1-7. (31) Hu, T.; Smith, M. D.; Dohner, E. R.; Sher, M. J.; Wu, X.; Trinh, M. T.; Fisher, A.; Corbett, J.; Zhu, X. Y.; Karunadasa, H. I.; Lindenberg, A. M. Mechanism for Broadband White-Light Emission from Two-Dimensional (110) Hybrid Perovskites. J. Phys. Chem. Lett. 2016, 7, 2258−2263. (32) Smith, M. D.; Jaffe, A.; Dohner, E. R.; Lindenberg A. M.; Karunadasa, H. I. Structural origins of broadband emission from layered Pb–Br hybrid perovskites. Chem. Sci. 2017, 8, 4497-4504. (33) Williams, R. T.; Song, K. S. The self-trapped exciton. J. Phys. Chem. Solids. 1990, 51, 679-716. (34) Dohner, E. R.; Hoke, E. T.; Karunadasa, H. I. Self-assembly of broadband white-light emitters. J. Am. Chem. Soc. 2014, 136, 1718−1721. (35) Lin, H.; Zhou, C.; Tian,Y.; Besara,T.; Neu, J.; Siegrist,T.; Ma, B. Bulk assembly of organic metal halide nanotubes. Chemical Science. 2017,8(12),8400–8404. (36)Wu, Z.; Li, L.; Ji, C.; Lin, G.; Wang, S.; Shen, Y.; Sun, Z.; Zhao, S.; Luo, J. Broad-BandEmissive Organic-Inorganic Hybrid Semiconducting Nanowires Based on an ABX3-Type Chain Compound. Inorg. Chem. 2017, 56 (15), 8776–878. (37) Vial, J. C.; Bsiesy, A.; Gaspard, F.; Herino, R.; Ligeon, M.; Muller, F.; Romestain, R.; Macfarlane, R. M. Mechanisms of Visible- Light Emission from Electro-Oxidized Porous Silicon. Phys. Rev. B: Condens. Matter Mater. Phys. 1992, 45, 14171−14177. (38) Kobitski, A. Yu.; Zhuravlev, K. S.; Wagner, H. P.; Zahn, D. R. T. Self-Trapped Exciton Recombination in Silicon Nanocrystals. Phys.Rev. B. 2001, 63, 115423: 1-5. (39) Sugawara, M. Theory of spontaneous-emission lifetime of Wannier excitons in mesoscopic semiconductor quantum disks. Physical Review B. 1995, 51(16), 10743–10754. (40) Kohler, A.; Bassler, H. Triplet states in organic semiconductors. Mater. Sci. Eng. 2009, R 66, 71–109.



(41) Mao, L.; Guo, P.; Kepenekian, M.; Hadar, I.; Katan, C.; Even, J.;Kanatzidis, M. G. Structural Diversity in White-light Emitting Hybrid Lead Bromide Perovskites. J. Am. Chem. Soc. 2018, 140 (40),13078–13088. (42) Stryer, L. Fluorescence energy transfer as a spectroscopic ruler. Annu. Rev.Biochem. 1978, 47, 819–846. (43) Lee, J.; Govorov, A. O.; Kotov, N. A. Bioconjugated superstructures of CdTe, nanowires and nanoparticles: Multistep cascade Fo¨rster resonance energy transfer and energy channeling. Nano Lett. 2005, 5, 2063–2069. (44) Ozbay, E. Plasmonics: merging photonics and electronics at nanoscale dimensions. Science. 2006, 311, 189–193. (45) Rasnik, I.; McKinney, S. A.; Ha, T. Surfaces and orientations: much to FRET about? Acc. Chem. Res. 2005, 38, 542–548. (46) Giepmans, B. N.; Adams, S. R.; Ellisman, M. H.; Tsien, R. Y. The fluorescent toolbox for assessing protein location and function. Science. 2006, 312, 217-224. (47) Bae, S. H. et al. Single-Layered Films of Diblock Copolymer Micelles Containing Quantum Dots and Fluorescent Dyes and Their Fluorescence Resonance Energy Transfer. Chem. Mater. 2008, 20, 4185–4187. (48) Clapp, A. R.; Medintz, I. L.;Mattoussi, H. Fo¨rster Resonance Energy Transfer Investigations Using Quantum-Dot Fluorophores. Chem Phys Chem. 2006, 7, 47–57. (49) Papavassiliou, G. C.; Mousdis, G. A.; Pagona, G.; Karousis, N.; Vidali, M. S. Room temperature enhanced blue–green, yellow–orange and red phosphorescence from some compounds of the type (CH3NH3)n−1(1-naphthylmethyl ammonium)2Pbn(ClxBr1−x)3n+1 (with n=1, 2 and 0≤x≤1) and related observations from similar compounds. J. Lumin. 2014, 149, 287–291. (50) Ema, K.; Inomata, M.; Kato, Y.; Kunugita, H.; Era, M. Nearly Perfect Triplet-Triplet Energy Transfer from Wannier Excitons to Naphthalene in Organic-Inorganic Hybrid Quantum-Well Materials. Phys. Rev. Lett. 2008, 100, 257401:1-4.


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TOC FIGURE


Resonantly Enhanced White-Light Emission Involving Energy and

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