New photothermal deflection technique to discriminate between heating and cooling

Fontenot, Ross S.; Mathur, V. K.; Barkyoumb, J. H.

doi:10.1016/j.jqsrt.2017.08.019

Cited by 12 publications

(8 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The generally accepted mechanism of QD UCPL is based on thermal-activation of defect states within the bandgap 18 , 19 , 21 , which implies low UCPL efficiency under typical excitation conditions. A few publications reported semiconductor nanomaterials with high power-conversion efficiency under sub-bandgap excitation 22 – 24 , which have been under debate in the recent literatures 17 , 25 , 26 .…”

Section: Introductionmentioning

confidence: 99%

Phonon-assisted up-conversion photoluminescence of quantum dots

Lin

Wang

et al. 2021

Nat Commun

View full text Add to dashboard Cite

Phonon-assisted up-conversion photoluminescence can boost energy of an emission photon to be higher than that of the excitation photon by absorbing vibration energy (or phonons) of the emitter. Here, up-conversion photoluminescence power-conversion efficiency (power ratio between the emission and excitation photons) for CdSe/CdS core/shell quantum dots is observed to be beyond unity. Instead of commonly known defect-assisted up-conversion photoluminescence for colloidal quantum dots, temperature-dependent measurements and single-dot spectroscopy reveal the up-conversion photoluminescence and conventional down-conversion photoluminescence share the same electron-phonon coupled electronic states. Ultrafast spectroscopy results imply the thermalized excitons for up-conversion photoluminescence form within 200 fs, which is 100,000 times faster than the radiative recombination rate of the exciton. Results suggest that colloidal quantum dots can be exploited as efficient, stable, and cost-effective emitters for up-conversion photoluminescence in various applications.

show abstract

Section: Introductionmentioning

confidence: 99%

Phonon-assisted up-conversion photoluminescence of quantum dots

Lin

Wang

et al. 2021

Nat Commun

View full text Add to dashboard Cite

show abstract

“…PDS is a very sensitive optical absorption technique based on measuring the heat that is dissipated when subbandgap light is being absorbed by the sample. [46][47][48] In amorphous materials, structural disorder causes self-localization of carriers and the spectral dependence of the optical absorption edge can be described as…”

Section: Resultsmentioning

confidence: 99%

Surface Passivation Treatment to Improve Performance and Stability of Solution‐Processed Metal Oxide Transistors for Hybrid Complementary Circuits on Polymer Substrates

et al. 2021

View full text Add to dashboard Cite

Hybrid integration of n-type oxide with p-type polymer transistors is an attractive approach for realizing high performance complementary circuits on flexible substrates. However, the stability of solution-processed oxide transistors is limiting the lifetime and reliability of such circuits. Oxygen vacancies are the main defect degrading metal oxide transistor performance when ambient oxygen adsorbs onto metal oxide films. Here, an effective surface passivation treatment based on negative oxygen ion exposure combined with UV light is demonstrated, that is able to significantly reduce surface oxygen vacancy concentration and improve the field effect mobility to values up to 41 cm 2 V −1 s −1 with high on-off current ratio of 10 8 . The treatment also reduces the threshold voltage shift after 2 days in air from 5 to 0.07 V. The improved stability of the oxide transistors also improves the lifetime of hybrid complementary circuits and stable operation of complementary, analog amplifiers is confirmed for 60 days in air. The suggested approach is facile and can be widely applicable for flexible electronics using low-temperature solution-processed metal oxide semiconductors.

show abstract

“…Adding to this, Xiong and co-workers 50 have suggested the cooling of individual hybrid perovskite nanoplatelets. An additional report by Fontenot et al 51,52 has likewise suggested the optical cooling of commercial, overcoated CdSe NCs. Because of these tantalizing hints that semiconductor nanostructures can be cooled, the remainder of this review focuses on explaining emission upconversion in colloidal semiconductor NCs and associated nanostructures, as well as illustrating the underlying hinderances to achieving laser-induced cooling.…”

Section: Towards Nanostructuresmentioning

confidence: 90%

“…50 (hybrid perovskite nanoplatelets), and refs. 51,52 (core/shell CdSe NCs). Concerns, however, exist regarding the validity of these studies, as outlined in ref.…”

Section: Prior Suggestions Of Nanostructure Laser Coolingmentioning

confidence: 99%

See 1 more Smart Citation

Progress in laser cooling semiconductor nanocrystals and nanostructures

et al. 2019

View full text Add to dashboard Cite

Over the past two decades, there have been sizable efforts to realize condensed phase optical cooling. To date, however, there have been no verifiable demonstrations of semiconductor-based laser cooling. Recently, advances in the synthesis of semiconductor nanostructures have led to the availability of high-quality semiconductor nanocrystals, which possess superior optical properties relative to their bulk counterparts. In this review, we describe how these nanostructures can be used to demonstrate condensed phase laser cooling. We begin with a description of charge carrier dynamics in semiconductor nanocrystals and nanostructures under both above gap and below-gap excitation. Two critical parameters for realizing laser cooling are identified: emission quantum yield and upconversion efficiency. We report the literature values of these two parameters for different nanocrystal/nanostructure systems as well as the measurement approaches used to estimate them. We identify CsPbBr 3 nanocrystals as a potential system by which to demonstrate verifiable laser cooling given their ease of synthesis, near-unity emission quantum yields and sizable upconversion efficiencies. Feasibility is further demonstrated through numerical simulations of CsPbBr 3 nanocrystals embedded in an aerogel matrix. Our survey generally reveals that optimized semiconductor nanocrystals and nanostructures are poised to demonstrate condensed phase laser cooling in the near future.

show abstract

New photothermal deflection technique to discriminate between heating and cooling

Cited by 12 publications

References 22 publications

Phonon-assisted up-conversion photoluminescence of quantum dots

Phonon-assisted up-conversion photoluminescence of quantum dots

Surface Passivation Treatment to Improve Performance and Stability of Solution‐Processed Metal Oxide Transistors for Hybrid Complementary Circuits on Polymer Substrates

Progress in laser cooling semiconductor nanocrystals and nanostructures

Contact Info

Product

Resources

About