Ultrafast selective extraction of hot holes from cesium lead iodide perovskite films

Shen, Qing; Ripolles, Teresa S.; Even, Jacky; Zhang, Yaohong; Liu, Feng; Izuishi, Takuya; Nakazawa, Naoki; Toyoda, Taro; Ogomi, Yuhei; Hayase, Shuzi

doi:10.1016/j.jechem.2018.01.006

Cited by 23 publications

(25 citation statements)

References 50 publications

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“…For <N 0 > ≈0.1, the η hot for EDT-NCs/Bphen is ≈72%. More recently, HC-extraction evidenced using the TA approach was also reported for a CsPbI 3 film with P3HT as the extraction layer by Shen et al [38] The near instantaneous disappearance of the hot-energy tail (within ≈0.3 ps) and the reduction of HC temperatures in CsPbI 3 /P3HT bilayers validate the efficient and extremely fast hot-hole injection into P3HT (Figure 10e). Comparatively, due to the faster HC cooling, the η hot of its bulk-film counterpart is approximately five times lower under similar photoexcitation conditions.…”

Section: Efficient Hc Extractionsupporting

confidence: 72%

“…Lastly, the cooled carriers will recombine (usually in nanosecond timescale -process 6). [22,[28][29][30][31][37][38][39][40][41][42][43][44][45] These studies include the 3) carrier-optical phonon interactions; 4) decay of optical phonons into acoustic phonons; 5) further phonon emission to thermal equilibrium; (6) onset of carrier recombination. Next, we trace the milestones of slow HC cooling phenomena in halide perovskites.…”

Section: Typical Hc Cooling Dynamicsmentioning

confidence: 99%

“…[117] TRTS is a very useful noncontact photoconductivity probe to investigate the HC transfer kinetics in NCs system. [38] Copyright 2018, Elsevier. e) TA spectra of the CsPbI 3 film with (red) and without (black) P3HT at 0.3 ps after 470 nm photoexcitation at pump fluence of 1.3 × 10 18 cm −3 .…”

Section: Efficient Hc Extractionmentioning

confidence: 99%

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

et al. 2019

Advanced Materials

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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: Efficient Hc Extractionsupporting

confidence: 72%

Section: Typical Hc Cooling Dynamicsmentioning

confidence: 99%

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

et al. 2019

Advanced Materials

247

326

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“…Such hot carriers have higher carrier temperature, T C , than the crystal lattice, which dissipates in a very short period of time (hundreds of fs) through a phonon emission process. The T C can be calculated by fitting the TA spectra (the fitting curves are provided in the Supporting Information, see Figure S6) above the band edge (between 1.7 and 2 eV) to a Boltzmann distribution9a,b,11,12

Δ A ([], E) \propto e^{- (E - E_{f}) / (k_{B} T_{c})}

where, E f is the quasi‐Fermi energy and k B is the Boltzmann constant. Figure d shows the T c of MAPbI 3 film drops from ≈1500 to 600 K within ≈2 ps after photoexcitation, implying that the excess energy of the carriers was released to the crystal lattice through nonradiative pathways.…”

Section: Resultsmentioning

confidence: 99%

“…With a few studies uncovering qualitatively different cooling behavior exhibited by perovskites in comparison to other conventional semiconductor materials used in solar cells . However, the extraction of these hot carriers before they quickly relax to the band edges still remains largely elusive for the MAPbI 3 perovskite films; although there are few works about the extraction from other perovskites systems, including MAPbBr 3 , CsPbI 3 , and CsPbBr 3 perovskite nanocrystals.…”

Section: Introductionmentioning

confidence: 99%

Why are Hot Holes Easier to Extract than Hot Electrons from Methylammonium Lead Iodide Perovskite?

Dursun

Yin

Türedi

et al. 2019

Advanced Energy Materials

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While these devices are amenable to mass manufacturing due to their relatively simple architecture, they are also limited in the solar spectrum that they can exploit, which is set by the bandgap energy of their absorber. Photons that exceed the bandgap's energy excite the charge-carriers to energy levels above the bandgap, where upon the carriers quickly relax back (i.e., cooldown) to the bandgap edge, essentially dissipating all energy in excess of the bandgap. This innate process of rapid hot carrier cooling, preceding the carrier recombination at the bandgap's edge, is a major source of loss in semiconductor materials that limits their photovoltaic performance. [3] In single junction solar cells such losses set an efficiency limit of 33% -known as the Shockley-Queisser (SQ) limit [3b] -on the harvestable solar energy. Potentially pushing the solar cell efficiencies beyond this limit entails overcoming the narrow time window of carrier cooling (≈hundreds of femtoseconds, fs) and addressing the energy-level alignment mismatch preventing the effective extraction of hot carriers from the absorbing semiconductor. Recently, solar cells based on a low-temperature solutionprocessable class of absorbing semiconductors, known as metal halide perovskites, have been the subject of intense investigation. The initial interest in these materials stemmed from the impressive efficiencies that their solar cells could achieve, despite their simple processing routes, offering a prospect for a cheap yet efficient photovoltaic technology (current power conversion efficiency ≈23%). [4] However, the scope of halide perovskite optoelectronics has expanded to encompass photodetectors, [5] scintillators, [6] light emitting diodes, [7] and lasers. [8] Understanding the cooling dynamics of hot carriers is of relevance to all these applications, and utilizing (the currently unutilized) hot carriers is potentially beneficial (varying extent) to all the aforementioned optoelectronic technologies.The study of hot carrier dynamics in methylammonium lead iodide (CH 3 NH 3 PbI 3 , or MAPbI 3 )-an archetypal perovskite solar cell material-has received significant attention over the last several years. [9] With a few studies uncovering qualitatively different cooling behavior exhibited by perovskites in comparison to other conventional semiconductor materials used Charge-carriers photoexcited above a semiconductor's bandgap rapidly thermalize to the band-edge. The cooling of these difficult to collect "hot" carriers caps the available photon energy that solar cells-including efficient perovskite solar cells-may utilize. Here, the dynamics and efficiency of hot carrier extraction from MAPbI 3 (MA = methylammonium) perovskite by spiro-OMeTAD (a hole-transporting layer) and TiO 2 (an electron-transporting layer) are investigated and explained using both ultrafast electronic spectroscopy and theoretical modeling. Time-resolved spectroscopy reveals a quasiequilibrium distribution of hot carriers forming upon excess-energy excitation of the perovsk...

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Challenges, Opportunities, and Prospects in Metal Halide Perovskites from Theoretical and Machine Learning Perspectives

Myung

Hajibabaei

Cha

et al. 2022

Advanced Energy Materials

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Metal halide perovskite (MHP) is a promising next generation energy material for various applications, such as solar cells, light emitting diodes, lasers, sensors, and transistors. MHPs show excellent mechanical, dielectric, photovoltaic, photoluminescence, and electronic properties, and such intriguing physical and chemical properties have drawn attention recently. However, there exists a chasm between the successful applications of MHPs and theoretical understandings. The difficulty arises from the intrinsic properties of MHPs, including structural disorder, ionic interactions, nonadiabatic effects, and composition diversity. Machine learning (ML) approaches have shown great promise as a tool to overcome the theoretical obstacles in many fields of science. In this perspective, the pending theoretical challenges from experiments are overviewed and promising ML approaches, including ab initio ML potentials, materials design/optimization models, and data mining strategies are proposed. Possible roles and pipelines of ML frameworks are highlighted to close the gap between experiment and theory in MHPs.

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Ultrafast selective extraction of hot holes from cesium lead iodide perovskite films

Abstract: International audienc

Cited by 23 publications

References 50 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

Why are Hot Holes Easier to Extract than Hot Electrons from Methylammonium Lead Iodide Perovskite?

Challenges, Opportunities, and Prospects in Metal Halide Perovskites from Theoretical and Machine Learning Perspectives

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