Direct Experimental Evidence for Photoinduced Strong-Coupling Polarons in Organolead Halide Perovskite Nanoparticles

Zheng, Kaibo; Abdellah, Mohamed; Zhu, Qiushi; Kong, Qingyu; Jennings, G.; Kurtz, C.; Messing, Maria E.; Niu, Yuran; Gosztola, David J.; Al–Marri, Mohammed J.; Zhang, Xiaoyi; Pullerits, Tõnu; Canton, Sophie E.

doi:10.1021/acs.jpclett.6b02046

Cited by 55 publications

(84 citation statements)

References 33 publications

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“…This short review of our time-resolved X-ray spectroscopic studies was aimed at stressing the advantages of an element-selective, time-resolved probe of photoex-is akin to phase space filling reported in optical studies of semiconductors, [29] and it suggests that electrons are free carriers in the CB. Further confirmation of the present observations is given by the recent ps XAS studies by Zheng et al [30] on CH 3 NH 3 PbBr 3 nanoparticles. They report a similar decrease of absorption around 13.045 keV at 100-150 ps time delay.…”

Section: Resultssupporting

confidence: 91%

Time-resolved Element-selective Probing of Charge Carriers in Solar Materials

Budarz

Santomauro

Rittmann-Frank

et al. 2017

Chimia

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We review our recent results on the implementation of picosecond (ps) X-ray absorption spectroscopy to probe the electronic and geometric structure of centres formed by photoexcitation of solar materials such as TiO2 polymorphs and inorganic Cs-based perovskites. The results show electron localization at Ti defects in TiO2 anatase and rutile and small hole polaron formation in the valence band of CsPbBr3, all within 80 ps. This method is promising for the study of the ultrafast time scales of such processes, especially with the advent of the Swiss X-ray Free Electron Laser (SwissFEL).

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Section: Resultssupporting

confidence: 91%

Time-resolved Element-selective Probing of Charge Carriers in Solar Materials

Budarz

Santomauro

Rittmann-Frank

et al. 2017

Chimia

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“…For instance, the photoluminescence of perovskites can be significantly broadened by the strong phonon coupling in the materials, thus influencing the light‐emitting properties . Besides, the carrier/exciton transport that strongly affects the performance of perovskite photovoltaics is closely correlated with the electron/exciton‐optical phonon scatterings . Hence, a systematic investigation of the phonon properties and their interactions with other quasiparticles in perovskites are necessary.…”

Section: Excitons and Related Phenomena In Metal Halide Perovskitesmentioning

confidence: 99%

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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“…4,38 Overall, while significant progress has been achieved in the study of the optoelectronic properties of this class of materials, there are still fundamental questions that remain unanswered. In particular, while the occurrence of polarons in CH3NH3PbI3 and other lead-halide perovskites has been demonstrated by both theory and experiments, 4,29,43 the distinct role and the complex interplay between the inorganic sub-lattice and the A-site cations, whether organic or not, still eludes a comprehensive characterization. In fact, even if distortions in the inorganic sub-lattice stabilize the localized charge, such a localization might be inaccessible in absence of a disordered dipole field generated by the A-site cations.…”

Section: Toc Graphicsmentioning

confidence: 99%

Charge Localization, Stabilization, and Hopping in Lead Halide Perovskites: Competition between Polaron Stabilization and Cation Disorder

et al. 2019

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Metal halide perovskites, of general formula ABX3, show a complex interplay of the inorganic BX3 sub-lattice and the organic/inorganic A-site cations, which likely determines some of their peculiar optoelectronic properties. Comprehension of the physics underlying this interaction may reveal further means of fine-tuning their optoelectronic response. Here, we investigate in depth charge/lattice interactions associated to the formation of polarons in different models of the prototypical CH3NH3PbI3 perovskite through advanced electronic-structure calculations. We demonstrate that charge localization, while induced by the disordered dipolar field of the organic

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Direct Experimental Evidence for Photoinduced Strong-Coupling Polarons in Organolead Halide Perovskite Nanoparticles

Cited by 55 publications

References 33 publications

Time-resolved Element-selective Probing of Charge Carriers in Solar Materials

Time-resolved Element-selective Probing of Charge Carriers in Solar Materials

Properties of Excitons and Photogenerated Charge Carriers in Metal Halide Perovskites

Charge Localization, Stabilization, and Hopping in Lead Halide Perovskites: Competition between Polaron Stabilization and Cation Disorder

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