7 research outputs found
Boosting the efficiency of transient photoluminescence microscopy using cylindrical lenses
Transient Photoluminescence Microscopy (TPLM) allows for the direct
visualization of carrier transport in semiconductor materials with sub
nanosecond and few nanometer resolution. The technique is based on measuring
changes in the spatial distribution of a diffraction limited population of
carriers using spatiotemporal detection of the radiative decay of the carriers.
The spatial resolution of TPLM is therefore primarily determined by the
signal-to-noise-ratio (SNR). Here we present a method using cylindrical lenses
to boost the signal acquisition in TPLM experiments. The resulting asymmetric
magnification of the photoluminescence emission of the diffraction limited spot
can increase the collection efficiency by more than a factor of 10,
significantly reducing acquisition times and further boosting spatial
resolution.Comment: 12 pages, 5 figures, and supporting informatio
Boosting the efficiency of transient photoluminescence microscopy using cylindrical lenses
Transient Photoluminescence Microscopy (TPLM) allows for the direct visualization of carrier transport in
semiconductor materials with sub nanosecond and few nanometer resolution. The technique is based on
measuring changes in the spatial distribution of a diffraction limited population of carriers using spatiotemporal detection of the radiative decay of the carriers. The spatial resolution of TPLM is therefore primarily determined by the signal-to-noise-ratio (SNR). Here we present a method using cylindrical lenses
to boost the signal acquisition in TPLM experiments. The resulting asymmetric magnification of the
photoluminescence emission of the diffraction limited spot can increase the collection efficiency by
more than a factor of 10, significantly reducing acquisition times and further boosting spatial resolutionWe acknowledge the support from the â(MAD2D-CM)-UAMâ
project funded by Comunidad de Madrid, by the Recovery,
Transformation and Resilience Plan, and by NextGenerationEU
from the European Union, as well as from the Spanish
Ministry of Science and Innovation under grant agreement
TED2021-131018B-C21 and through the RamĂłn y Cajal
program (F.P. RYC-2017-23253
Exciton diffusion in two-dimensional metal-halide perovskites
Two-dimensional layered perovskites are attracting increasing attention as more robust analogues to the conventional three-dimensional metal-halide perovskites for both light harvesting and light emitting applications. However, the impact of the reduced dimensionality on the optoelectronic properties remains unclear, particularly regarding the spatial dynamics of the excitonic excited state within the two-dimensional plane. Here, we present direct measurements of exciton transport in single-crystalline layered perovskites. Using transient photoluminescence microscopy, we show that excitons undergo an initial fast diffusion through the crystalline plane, followed by a slower subdiffusive regime as excitons get trapped. Interestingly, the early intrinsic diffusivity depends sensitively on the choice of organic spacer. A clear correlation between lattice stiffness and diffusivity is found, suggesting excitonâphonon interactions to be dominant in the spatial dynamics of the excitons in perovskites, consistent with the formation of excitonâpolarons. Our findings provide a clear design strategy to optimize exciton transport in these systemsThis work has been supported by the Spanish Ministry of Economy and Competitiveness through The âMarĂa de Maeztuâ Program for Units of Excellence in R&D (MDM-2014-0377). M.S. acknowledges the financial support of a fellowship from âla Caixaâ Foundation (ID 100010434). The fellowship code is LCF/BQ/IN17/11620040. M.S. has received funding from the European Unionâs Horizon 2020 research and innovation program under the Marie SkĆodowska-Curie grant agreement No. 713673. F.P. acknowledges support from the Spanish Ministry for Science, Innovation, and Universities through the state program (PGC2018-097236-A-I00) and through the RamĂłn y Cajal program (RYC-2017-23253), as well as the Comunidad de Madrid Talent Program for Experienced Researchers (2016-T1/IND-1209). N.A., M.M. and R. D.B. acknowledges support from the Spanish Ministry of Economy, Industry and Competitiveness through Grant FIS2017-86007-C3-1-P (AEI/FEDER, EU). E.P. acknowledges support from the Spanish Ministry of Economy, Industry and Competitiveness through Grant FIS2016-80434-P (AEI/FEDER, EU), the RamĂłn y Cajal program (RYC-2011- 09345) and the Comunidad de Madrid through Grant S2018/ NMT-4511 (NMAT2D-CM). S.P. acknowledges financial support by the VILLUM FONDEN via the Centre of Excellence for Dirac Materials (Grant No. 11744
Broadband-tunable spectral response of perovskite-on-paper photodetectors using halide mixing
Paper offers a low-cost and widely available substrate for electronics. It
posses alternative characteristics to silicon, as it shows low density and
high-flexibility, together with biodegradability. Solution processable
materials, such as hybrid perovskites, also present light and flexible
features, together with a huge tunability of the material composition with
varying optical properties. In this study, we combine paper substrates with
halide-mixed perovskites for the creation of low-cost and easy-to-fabricate
perovskite-on-paper photodetectors with a broadband-tunable spectral response.
From the bandgap tunability of halide-mixed perovskites we create
photodetectors with a cut-off spectral onset that ranges from the NIR to the
green, by increasing the bromide content on MAPb(IBr)
perovskite alloys. The devices show a fast and efficient response. The best
performances are observed for the pure I and Br perovskite compositions, with a
maximum responsivity of 376 mA/W on the MAPbBr device. This study provides
an example of the wide range of possibilities that the combination of solution
processable materials with paper substrates offer for the development of
low-cost, biodegradable and easy-to-fabricate devices.Comment: 3 main text figures, 8 supp info figure
Efficient Interlayer Exciton Transport in Two-Dimensional Metal-Halide Perovskites.
We present transient microscopy measurements of interlayer energy transport in (PEA)2PbI4 perovskite. We find efficient interlayer exciton transport (0.06 cm2/s), which translates into a diffusion length that exceeds 100 nm and a sub-ps timescale for energy transfer. While still slower than in-plane exciton transport (0.2 cm2/s), our results show that excitonic energy transport is considerably less anisotropic than charge-carrier transport for 2D perovskites
Halide mixing inhibits exciton transport in two-dimensional perovskites despite phase purity
Halide mixing is one of the most powerful techniques to tune the optical bandgap of metal-halide perovskites. However, halide mixing has commonly been observed to result in phase segregation, which reduces excited-state transport and limits device performance. While the current emphasis lies on the development of strategies to prevent phase segregation, it remains unclear how halide mixing may affect excited-state transport even if phase purity is maintained. Here, we study exciton transport in phase pure mixed-halide 2D perovskites of (PEA)2Pb(I1-xBrx)4. Using transient photoluminescence microscopy, we show that, despite phase purity, halide mixing inhibits exciton transport. We find a significant reduction even for relatively low alloying concentrations. By performing Brownian dynamics simulations, we are able to reproduce our experimental results and attribute the decrease in diffusivity to the energetically disordered potential landscape that arises due to the intrinsic random distribution of alloying sitesThis work has been supported by the Spanish Ministry of Economy and Competitiveness through the âMari Ì a de Maeztuâ Program for Units of Excellence in R&D (MDM-2014-0377). M.S. acknowledges the financial support through a Doc.Mobility Fellowship from the Swiss National Science Foundation (SNF) with grant number 187676. In addition, M.S. acknowledges the financial support of a fellowship from âla Caixaâ Foundation (ID 100010434). The fellowship code is LCF/BQ/IN17/11620040. Further, M.S. has received funding from the European Unionâs Horizon 2020 research and innovation program under the Marie SkĆodowska-Curie grant agreement No. 713673. F.P. acknowledges support from the Spanish Ministry for Science, Innovation, and Universities through the state program (PGC2018-097236-A-I00) and through the RamĂłn y Cajal program (RYC-2017-23253), as well as the Comunidad de Madrid Talent Program for Experienced Researchers (2016-T1/IND-1209). M.M., N.C., and R.D.B. acknowledge support from the Spanish Ministry of Economy, Industry, and Competitiveness through Grant FIS2017-86007-C3-1-P (AEI/FEDER, EU). D.N.C. acknowledges the support of the Rowland Fellowship at the Rowland Institute at Harvard University and the Department of Electrical Engineering at Stanford University. M.K.G. acknowledges the support of National Science Foundation Track 1 EPSCoR funding under the grant no. 1757220. D.A.K. acknowledges the support of a Rowland Foundation Postdoctoral Fellowshi