Transient absorption imaging of carrier dynamics in disordered semiconductors

Hill, Andrew H.; Smyser, Kori E.; Kennedy, Casey L.; Massaro, Eric S.; Grumstrup, Erik M.

doi:10.1117/12.2262664

Cited by 2 publications

(2 citation statements)

References 35 publications

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“…While dependent on signal to noise levels, a typical 100 × 100 pixel image can be collected in 3−4 min of experimental time. 12 Although the complementarity between ΔT/T and ΔR/R images is generally present across the entirety of the domain, there are regions that appear to deviate. These regions are often near edges or exhibit significant surface roughness, which suggests that scattering, which reduces the overall FP mode contrast, 13 is likely responsible for the deviation.…”

Section: Resultsmentioning

confidence: 99%

High-Repetition Rate Broadband Pump–Probe Microscopy

Piland

Grumstrup

2019

J. Phys. Chem. A

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Pump–probe microscopy has recently emerged as an important tool for characterizing the effects of nanoscale chemical and compositional heterogeneity on the optoelectronic properties of material systems. This article describes the development of broadband pump–probe microscopy, which utilizes a high-speed line camera and high repetition rate amplified fiber laser to collect full transient spectra at 30+ kHz and with sub 100 fs temporal resolution. The broadband imaging and spectroscopic capabilities of the technique are demonstrated on individual micron-sized lead halide perovskite domains. Also discussed are several challenges associated with collecting broadband transient spectra from sub-micron sample areas, including the importance of careful design of imaging optics to minimize the effects of spherical and chromatic aberrations, detector considerations, and the importance of spot size effects on absolute signal size.

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Section: Resultsmentioning

confidence: 99%

High-Repetition Rate Broadband Pump–Probe Microscopy

Piland

Grumstrup

2019

J. Phys. Chem. A

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“…39 Similarly, transient reflectivity, while complicated by the Fabry−Perot mode interference that contributes to the signal, is predominately sensitive to changes in the dielectric function near the surface, where there is a large mismatch in the index of refraction. 40 While it is difficult at present to identify the specific morphological defects that give rise to reduced charge carrier mobility and reduced diffraction pattern contrast, the most likely candidate is anisotropic lattice strain, caused by, perhaps, a mismatch of thermal expansion coefficients upon cool-ing. 27,41,42 In the band picture of charge carrier transport, disruption of the periodicity of the lattice will reduce the mean scattering time of charge carriers, reducing the observed mobility.…”

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confidence: 99%

Direct Correlation of Charge Carrier Transport to Local Crystal Quality in Lead Halide Perovskites

Hickey

Grumstrup

2020

Nano Lett.

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Although solution processing methods provide an attractive route toward development of low-cost functional materials, these accessible fabrication approaches can engender high concentrations of microscopic structural defects that are detrimental to performance. In lead halide perovskites, structural disorder derived from solution processing has been implicated as an important determiner of photophysical properties. However, a direct correlation between the functional properties of these materials and the local crystal structure in which non-equilibrium states evolve has remained elusive, in part because structural heterogeneities occur on length scales that defy conventional characterization techniques. To address this knowledge gap, we have combined ultrafast pump–probe microscopy and electron backscattering diffraction to directly correlate charge carrier transport with the local diffraction pattern contrast, an indicator of crystal quality. Spatial correlation of these measurements strongly suggests that even on individual single crystal CsPbBr3 domains, microscopic variability in the crystal quality profoundly impacts the efficiency of charge carrier transport.

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Transient absorption imaging of carrier dynamics in disordered semiconductors

Cited by 2 publications

References 35 publications

High-Repetition Rate Broadband Pump–Probe Microscopy

High-Repetition Rate Broadband Pump–Probe Microscopy

Direct Correlation of Charge Carrier Transport to Local Crystal Quality in Lead Halide Perovskites

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