Nonequilibrium dynamics of hot carriers and hot phonons in CdSe and GaAs

Prabhu, S. S.; Vengurlekar, A. S.; Roy, Susmita; Shah, Jagdeep

doi:10.1103/physrevb.51.14233

Cited by 69 publications

(57 citation statements)

References 38 publications

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“…[54][55][56] This bottleneck effect usually occurs in highly excited semiconductors and has recently been observed in perovskites in the presence of a nonequilibrium LO-phonon population that leads to reduced net LO-phonon emission and reheating of carriers, thus slowing the HC cooling. [54][55][56] This bottleneck effect usually occurs in highly excited semiconductors and has recently been observed in perovskites in the presence of a nonequilibrium LO-phonon population that leads to reduced net LO-phonon emission and reheating of carriers, thus slowing the HC cooling.…”

Section: Hot-phonon Bottleneck Effectmentioning

confidence: 99%

Slow Hot‐Carrier Cooling in Halide Perovskites: Prospects for Hot‐Carrier Solar Cells

et al. 2019

Advanced Materials

247

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rapidly (within hundreds of femtoseconds), making HCs extraction extremely challenging. A reduced HC cooling rate in solar absorbers is therefore a key material criterion for realizing HCSC.Halide perovskites possess novel slow HC cooling properties favorable for development as HCSC. Since the first reports of slow HC cooling (≈0.4 ps) in MAPbI 3 polycrystalline thin films, [7,8] there have been growing interests about this novel phenomenon. Li et al. reported a drastic slowdown of HC cooling by a further two orders in MAPbBr 3 colloidal nanocrystals (≈30 ps) at high pump fluence and demonstrated efficient (≈83%) extraction of HCs with an energy-selective organic layer. [9] Long HC transport lengths (≈600 nm) in MAPbI 3 thin films were visualized by Huang et al. [10] These exciting findings forebode the potential of perovskite HCSCs that could dramatically boost perovskite solar cell efficiencies beyond their SQ limits. Presently, the origins and mechanisms of slow HC cooling in halide perovskites remain fragmented and confusing with disparate models being proposed. A clear understanding of the intrinsic photophysics of HC cooling is essential for further technological developments.In this review, we examine the milestones and advancements of slow HC cooling in halide perovskites and distill their photophysical mechanisms. We begin with a brief introduction of the operation principles of HCSCs and carrier relaxation processes, followed by highlighting the seminal experimental and theoretical works on slow HC cooling in halide perovskites, before explicating their origins and mechanisms. A developmental toolbox for engineering slow HC cooling in halide perovskites and developing new perovskite materials with slower HC cooling will also be discussed. Lastly, we highlight the challenges and opportunities for perovskite HCSCs. How Hot Carriers Can Be Used?We begin with a quick overview of the several concepts for highefficiency solar cells. Figure 1a illustrates the energy band diagram of a typical single junction solar cell with its major energy loss processes following light illumination. [11,12] In all solar cells, photons possessing energies greater than the semiconductor bandgap can create free carriers or excitons with excess energies above the bandgap. These carriers or excitons with a temperature higher than the lattice temperature are termed "hot Rapid hot-carrier cooling is a major loss channel in solar cells. Thermodynamic calculations reveal a 66% solar conversion efficiency for single junction cells (under 1 sun illumination) if these hot carriers are harvested before cooling to the lattice temperature. A reduced hot-carrier cooling rate for efficient extraction is a key enabler to this disruptive technology. Recently, halide perovskites emerge as promising candidates with favorable hot-carrier properties: slow hot-carrier cooling lifetimes several orders of magnitude longer than conventional solar cell absorbers, longrange hot-carrier transport (up to ≈600 nm), and highly efficient hot-carrier extractio...

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Section: Hot-phonon Bottleneck Effectmentioning

confidence: 99%

Slow Hot‐Carrier Cooling in Halide Perovskites: Prospects for Hot‐Carrier Solar Cells

et al. 2019

Advanced Materials

247

326

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“…In GaAs quantum wells, it is well known that the cooling rate of the hot-carrier and/or hot-phonon effect depends strongly on excitation intensity [10,11]. In CdSe thin crystal, the large reduction in hot-carrier energy relaxation rate caused by hot-phonon effects was observed [13,14], and this energy loss rate as a result of the hot-phonon effects in CdSe is ten times larger than that in GaAs [16].…”

Section: Introductionmentioning

confidence: 91%

Time-resolved absorption studies of the ZnSe/ZnSTe superlattice

Wang

Sou

Wong

et al. 2001

Superlattices and Microstructures

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“…11,29,30 This interaction favors optical phonons near the center of the Brillouin zone ͑BZ͒ since the rate matrix elements are proportional to 1 / q 2 , where q is the phonon wave vector. 31 If excitation of carriers takes place in the ⌫ valley, the photoexcited carrier density is high ͑տ10 20 cm −3 ͒ and the energy of the photoexcited carriers is larger than that of the side valley minimums ͑L and/or X͒, the electrons can scatter quickly ͑on the order of 100 fs͒ to these valleys. 51 The electrons in the side valleys return back slowly ͑on a time scale Ͼ1 ps͒ to the ⌫ valley.…”

Section: ‫ץ‬ ‫ץ‬Zmentioning

confidence: 99%

Influence of lattice heating time on femtosecond laser-induced strain waves in InSb

et al. 2008

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Femtosecond laser-induced strain waves in InSb are studied by means of time-resolved x-ray diffraction. The temporal evolution of the measured x-ray diffracted intensity reveals that the lattice dynamics depends on the time scale of energy transfer from excited carriers to the lattice. A framework that accounts for this energytransfer time ͑lattice heating time͒ is presented and applied to model the fluence dependence of the transient x-ray diffraction data. In this model the initial strain wave dynamics depends crucially on the lattice heating time, which decreases with increasing fluence.

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Nonequilibrium dynamics of hot carriers and hot phonons in CdSe and GaAs

Cited by 69 publications

References 38 publications

Slow Hot‐Carrier Cooling in Halide Perovskites: Prospects for Hot‐Carrier Solar Cells

Slow Hot‐Carrier Cooling in Halide Perovskites: Prospects for Hot‐Carrier Solar Cells

Time-resolved absorption studies of the ZnSe/ZnSTe superlattice

Influence of lattice heating time on femtosecond laser-induced strain waves in InSb

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