Low‐Temperature Absorption, Photoluminescence, and Lifetime of CsPbX<sub>3</sub> (X = Cl, Br, I) Nanocrystals

Diroll, Benjamin T.; Zhou, Hua; Schaller, Richard D.

doi:10.1002/adfm.201800945

Cited by 221 publications

(238 citation statements)

References 57 publications

(96 reference statements)

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“…Usually, a facile thermal treatment process (e.g., ≈90 °C) is necessary for obtaining high‐performance QD‐based optoelectronic devices. But, for perovskite QDs, such thermal annealing could obviously decrease the PL properties resulting from an increase of nonradiative recombination centers, perhaps, due to the loss of organic ligands on the surface of QDs . The PLQY of primal QD films decreased to 47% with a reduction of 20% after treated at 90 °C for 5 min.…”

Section: Summary Of the Materials And Device Performance Parameters Ofmentioning

confidence: 99%

Organic–Inorganic Hybrid Passivation Enables Perovskite QLEDs with an EQE of 16.48%

et al. 2018

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Highly efficient perovskite QLEDs can be realized when QD films possess two crucial synergistic parameters: highly luminescent features and effective electric transport properties. Regarding the emissive properties of QD films, although long organic ligands perfectly passivated the QD's surface and endowed ink with the near-unity luminescent properties with a PLQY approaching 100%, [11,12] the films generally exhibited a relatively low PLQY of about 40% due to the formation of nonradiative recombination centers. This phenomenon results from the dynamic characteristic of the bonding between the QD's surface and organic capping ligands, leading to the mismatched ligands during the film-forming process. [13,14] Meanwhile, these ligands act as electrically insulating layers on the QD's surface resulting in inefficient carrier injection and transportation, [15,16] which are detrimental to device performance. To enhance the electric properties of QD films, much attention [17,18] has been devoted to the development of ligand strategies that minimize the interparticle spacing. For example, Li et al. demonstrated an effective enhancement in electrical properties and EQE of CsPbBr 3 QLEDs through the control of surface ligand density. [9] Through ligand-exchange strategies, [8,19] a relatively short (C12) ligand, didodecyl dimethyl ammonium bromide (DDAB), was used to enhance device performance, obtaining an EQE of 8.73% under an effective washing process. Unfortunately, these methods are still based on long organic ligands, which cannot render the QD solid with ideal carrier injection and transportation features. Thus, it is significantly crucial to find an effective and feasible strategy to control the surface state of perovskite QDs, which could guarantee the high exciton recombination and carrier injection in constructing high-performance electroluminescent (EL) devices.Inorganic ligands with less space separation among particles could effectively enhance the electrical properties of QD films. [20,21] Meanwhile, they also improved the PL features through the reduce of the defect-related nonradiative recombination, which has been proven in traditional QDs. [22][23][24][25] For example, the halide-related ligands have improved the luminescent feature and radiative recombination in Cd-based QDs, which was realized by the ligand-exchange process. [20,26,27] But such a strategy is not feasible for perovskite QDs because they Perovskite quantum dots (QDs) with high photoluminescence quantum yields (PLQYs) and narrow emission peak hold promise for next-generation flexible and high-definition displays. However, perovskite QD films often suffer from low PLQYs due to the dynamic characteristics between the QD's surface and organic ligands and inefficient electrical transportation resulting from long hydrocarbon organic ligands as highly insulating barrier, which impair the ensuing device performance. Here, a general organic-inorganic hybrid ligand (OIHL) strategy is reported on to passivate perovskite QDs for highly efficient el...

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Section: Summary Of the Materials And Device Performance Parameters Ofmentioning

confidence: 99%

Organic–Inorganic Hybrid Passivation Enables Perovskite QLEDs with an EQE of 16.48%

et al. 2018

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“…Magnetoabsorption, temperature dependence of photoluminescence, and optical absorption as well as theoretical calculations have been applied to determine the exciton binding energies in hybrid and all‐inorganic perovskites. MAPbI 3 as the prototype of perovskites in photovoltaics has been mostly discussed in these studies.…”

Section: Excitons and Related Phenomena In Metal Halide Perovskitesmentioning

confidence: 99%

“…Along with the increased research on 2D perovskites, much attention has been paid to examining the exciton binding energies of perovskite nanostructures such as nanoplatelets, nanosheets, nanowires, nanocubes, and nanocrystals/quantum dots . To compare the excitonic properties of 3D bulk and nanostructure perovskites, Zhang et al reported an E b value of ≈375 meV for MAPbBr 3 quantum dots while ≈65 meV for the 3D counterpart .…”

Section: Excitons and Related Phenomena In Metal Halide Perovskitesmentioning

confidence: 99%

“…Despite the raised studies for hybrid perovskite nanostructures, understanding of the excitonic behavior in all‐inorganic perovskite nanostructures is also very crucial for the optoelectronic applications. The exciton binding energy of all‐inorganic perovskite nanostructures has been reported in the range of tens to hundreds of meV, depending on the morphology and the halide component . For instance, Li et al observed 0D to 2D transition of excitons in colloidal CsPbBr 3 nanoplatelets as the lateral size increases from 7.3 to 14.8 nm .…”

Section: Excitons and Related Phenomena In Metal Halide Perovskitesmentioning

confidence: 99%

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Properties of Excitons and Photogenerated Charge Carriers in Metal Halide Perovskites

2019

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their great success in photovoltaics (PVs), with a phenomenally rapid rise of the power conversion efficiency (PCE) from 3.8% [1] to over 23% [2,3] in the past few years. Such high PCE of perovskite solar cells has been ascribed to the ultralong carrier lifetimes, [4][5][6][7][8] long carrier diffusion lengths, [9][10][11][12][13][14] and the extraordinarily defect tolerance. [15][16][17] Following the success of perovskites in photovoltaics, research on light-emitting diodes (LEDs), [18,19] amplified spontaneous emission (ASE) or lasers, [20][21][22][23][24] and photodetectors [25][26][27][28][29] have also gained substantial interests. Meanwhile, the rapid progress of MHPs on various applications spurred a flurry of photophysical studies in order to understand the origin of the high performance of these devices, of which the nature of the photoexcitation species has been mostly debated. [5,22,30,31] Since the photoexcitation states near the bandgap affect the key processes such as charge transport and light emission of optoelectronic devices, there is no doubt that the investigation of electronic excitations near the optical band edge is crucial for MHPs. Such knowledge is essential not only for understanding the correlation between the fundamental photophysics and device performances, but also offering a guideline for their further applications with improved performances. Generally, there are two kinds of photoexcitations near the band edge for direct bandgap semiconductors: free carriers and excitons. Exciton binding energy that reflects the Coulomb interaction strength between photoexcited electrons and holes determines the balance of the populations between the two species. Typically, inorganic semiconductors are free-carrier materials with the exciton binding energies only in few meV at room temperature and their excited states being populated principally by free carriers. While organic semiconductors are excitonic materials with the exciton binding energies in hundreds of meV and thus excitons prevailing in the excited states. Whereas, MHPs that combine some merits of organic and inorganic semiconductors seem to stand for an exotic class of semiconductors between these two limiting cases, with the experimentally determined exciton binding energy varying in a wide range of 2 to more than 50 meV for the prototype perovskite MAPbI 3 . [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48] Such large variations of the exciton binding energies reported for MHPs give rise to a strongly debated question, that is, whether free carriers or excitons are generated upon photoexcitation? In other words, what is the nature of the photoexcitation species Metal halide perovskites (MHPs) have recently attracted great attention from the scientific community due to their excellent photovoltaic performance as well as their tremendous potential for other optoelectronic applications such as light-emitting diodes, lasers, and photodetectors. Despite the rapid progress in device applications, a solid unders...

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“…It can be seen that the theoretically calculated E b values of CsPbCl 3 and CsPbBr 3 are greater than the thermal energy value at RT, which indicates that CsPbCl 3 and CsPbBr 3 are optically more favorable. In fact, the relative accuracy of theoretical calculations was confirmed by experimental temperature‐dependent absorption, optical absorption, and magnetoabsorption …”

Section: Crystal Structure and Optoelectronic Properties Of Perovskitmentioning

confidence: 78%

Metal halide perovskite nanocrystals and their applications in optoelectronic devices

Wang

et al. 2019

InfoMat

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In recent years, metal halide perovskite nanocrystals (NCs) have been favored by many researchers due to their unique properties including long carrier diffusion length, high carrier mobility, tunable emission wavelength, and narrow full width at half maximum, making them great application potentials in optoelectronic devices. The photoluminescence quantum yields of perovskite NCs are nearly 100%, and the device efficiency of perovskite NC‐based light‐emitting diodes (LEDs) has been improved significantly from below 0.1% to over 20%. In addition, perovskite NC‐based solar cells and photodetectors have also developed rapidly in recent years. Here, we summarize the synthesis and the basic optoelectronic properties of metal halide perovskite NCs and introduce their applications in LEDs, solar cells, and photodetectors.

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Low‐Temperature Absorption, Photoluminescence, and Lifetime of CsPbX₃ (X = Cl, Br, I) Nanocrystals

Cited by 221 publications

References 57 publications

Organic–Inorganic Hybrid Passivation Enables Perovskite QLEDs with an EQE of 16.48%

Organic–Inorganic Hybrid Passivation Enables Perovskite QLEDs with an EQE of 16.48%

Properties of Excitons and Photogenerated Charge Carriers in Metal Halide Perovskites

Metal halide perovskite nanocrystals and their applications in optoelectronic devices

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Low‐Temperature Absorption, Photoluminescence, and Lifetime of CsPbX3 (X = Cl, Br, I) Nanocrystals

Cited by 221 publications

References 57 publications

Organic–Inorganic Hybrid Passivation Enables Perovskite QLEDs with an EQE of 16.48%

Organic–Inorganic Hybrid Passivation Enables Perovskite QLEDs with an EQE of 16.48%

Properties of Excitons and Photogenerated Charge Carriers in Metal Halide Perovskites

Metal halide perovskite nanocrystals and their applications in optoelectronic devices

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Low‐Temperature Absorption, Photoluminescence, and Lifetime of CsPbX₃ (X = Cl, Br, I) Nanocrystals