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August 17, 2020 September 9, 2026

Optical Properties of Organic/Inorganic Perovskite Microcrystals through the Characterization of Fabry-Pérot Resonances - Notes

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Published abstract

A precise knowledge of the optical properties, specifically the refractive index, of organic/inorganic perovskites, is essential for pushing forward the performance of the current photovoltaic devices that are being developed from these materials. Here we show a robust method for determining the real and the imaginary part of the refractive index of MAPbBr₃ thin films and micrometer size single crystals with planar geometry. The simultaneous fit of both the optical transmittance and the photoluminescence spectra to theoretical models defines unambiguously the refractive index and the crystal thickness. Because the method relies on the optical resonance phenomenon occurring in these microstructures, it can be used to further develop optical microcavities from perovskites or from other optical materials.

Figures

Figure 1 from Optical Properties of Organic/Inorganic Perovskite Microcrystals
Figure 1. Summary. Diagram showing the OT (a) and PL (b) experiments. (b1) Effect of the pump and PL propagation losses over the forward PL response.

© 2020 The Royal Society of Chemistry. Source: F. Ramiro-Manzano et al., Dalton Transactions 49(36), 12798-12804 (2020), DOI 10.1039/D0DT02254C. Reproduced by the authors in accordance with RSC author reuse rights.

Figure 2 from Optical Properties of Organic/Inorganic Perovskite Microcrystals
Figure 2. Summary. Transmittance (blue line) and Normalized PL (red line) spectra for different objectives: N.A. 0 (a), N.A.

© 2020 The Royal Society of Chemistry. Source: F. Ramiro-Manzano et al., Dalton Transactions 49(36), 12798-12804 (2020), DOI 10.1039/D0DT02254C. Reproduced by the authors in accordance with RSC author reuse rights.

The maps compare calculated transmittance (a) and normalized photoluminescence (b) for a MAPbBr3 planar cavity as its thickness increases from 1 to 20.85 µm at a collection numerical aperture of 0.26. The oblique traces follow successive Fabry-Perot modes: increasing thickness reduces their free spectral range, while angular averaging progressively lowers the visibility of the resonances, particularly in photoluminescence. The calculation uses the complex refractive-index dispersion obtained from the simultaneous fit of the experimental transmittance and photoluminescence spectra in Figure 4.
Figure 3. Summary. The maps compare calculated transmittance (a) and normalized photoluminescence (b) for a MAPbBr3 planar cavity as its thickness increases from 1 to 20.85 µm at a collection numerical aperture of 0.26. The oblique traces follow successive Fabry-Perot modes: increasing thickness reduces their free spectral range, while angular averaging progressively lowers the visibility of the resonances, particularly in photoluminescence. The calculation uses the complex refractive-index dispersion obtained from the simultaneous fit of the experimental transmittance and photoluminescence spectra in Figure 4.

© 2020 The Royal Society of Chemistry. Source: F. Ramiro-Manzano et al., Dalton Transactions 49(36), 12798-12804 (2020), DOI 10.1039/D0DT02254C. Reproduced by the authors in accordance with RSC author reuse rights.

Figure 4 from Optical Properties of Organic/Inorganic Perovskite Microcrystals
Figure 4. Summary. (a) Optical microscopy image of the measured MAPbBr₃ crystal microcavity (square structure at the center of the image). (b) and (c) Experimental data and fitted curves for the OT and the PL spectra respectively.

© 2020 The Royal Society of Chemistry. Source: F. Ramiro-Manzano et al., Dalton Transactions 49(36), 12798-12804 (2020), DOI 10.1039/D0DT02254C. Reproduced by the authors in accordance with RSC author reuse rights.

How to cite

Article access and reuse

The Version of Record is available from the Royal Society of Chemistry and is not hosted on this website. RSC authors retain the right to reuse their own figures on personal websites when the original article is properly acknowledged. The four figures below are complete, unmodified compositions extracted from the article PDF.

Related publications

Connections within F. Ramiro-Manzano's publication record, selected from shared research topics and evidence reviewed in the source papers.

Figure 1. Schematic representation of the electric contact on the microcrystalline samples, showing the irradiation objective at the bottom part controlled with a piezoelectric stage.
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This later paper extends the research direction developed in Optical Properties of Organic/Inorganic Perovskite Microcrystals through the Characterization of Fabry-Pérot Resonances. This study moves from optical resonances to spatially resolved charge transport in individual lead-bromide perovskite crystals. Scanning photocurrent microscopy separates the two transport regimes found in three-dimensional crystals from the single dominant regime in multidimensional 2D-3D crystals and exposes crystal edges as important recombination regions.

What this paper adds to the related work

This paper provides an earlier basis for the later development reported in Scanning Photocurrent Microscopy in Single Crystal Multidimensional Hybrid Lead Bromide Perovskites. This work uses the Fabry-Perot fringes of individual MAPbBr3 microcrystals as a source of quantitative information. A simultaneous fit of transmittance and photoluminescence retrieves crystal thickness and the real and imaginary parts of the refractive index near the band edge, while defining when a planar microcrystal behaves as an optical cavity.

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What the related paper adds

This later paper extends the research direction developed in Optical Properties of Organic/Inorganic Perovskite Microcrystals through the Characterization of Fabry-Pérot Resonances. This paper characterizes hydrated molybdenum cluster single crystals as optically active and electrically responsive microstructures. Their size- and orientation-dependent photoluminescence, visible photocurrent and Fabry-Perot behaviour extend single-crystal cavity and transport measurements beyond lead-halide perovskites to a distinct cluster-based material family.

What this paper adds to the related work

This paper provides an earlier basis for the later development reported in Optoelectronic properties of octahedral molybdenum cluster-based materials at a single crystal level. This work uses the Fabry-Perot fringes of individual MAPbBr3 microcrystals as a source of quantitative information. A simultaneous fit of transmittance and photoluminescence retrieves crystal thickness and the real and imaginary parts of the refractive index near the band edge, while defining when a planar microcrystal behaves as an optical cavity.

Complete Figure 1 composition from the CrI3 hyperspectral microscopy article
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What the related paper adds

This later paper extends the research direction developed in Optical Properties of Organic/Inorganic Perovskite Microcrystals through the Characterization of Fabry-Pérot Resonances. This study maps the complex dielectric function of CrI3 from the monolayer to the mesoscale using wide-field hyperspectral transmission microscopy. A simultaneous fit of spectra from many flakes and thicknesses to a Fabry-Perot and Lorentz-oscillator model reveals a nonmonotonic optical evolution with distinct few-layer, multilayer and bulk regimes, connecting the optical response to changes in electronic structure and magnetism.

What this paper adds to the related work

This paper provides an earlier basis for the later development reported in Monolayer-to-Mesoscale Modulation of the Optical Properties in 2D CrI3 Mapped by Hyperspectral Microscopy. This work uses the Fabry-Perot fringes of individual MAPbBr3 microcrystals as a source of quantitative information. A simultaneous fit of transmittance and photoluminescence retrieves crystal thickness and the real and imaginary parts of the refractive index near the band edge, while defining when a planar microcrystal behaves as an optical cavity.

Figure 3: CsPbBr3 nanowire characterization
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What the related paper adds

This earlier paper establishes a scientific basis for Optical Properties of Organic/Inorganic Perovskite Microcrystals through the Characterization of Fabry-Pérot Resonances. This paper converts low-cost CD and DVD surface profiles into moulds for aligned CsPbBr3 and MAPbBr3 nanowires. The process controls wire width and alignment at room temperature, allows transfer to other substrates, and demonstrates bright photoluminescence together with guided light propagation over distances longer than twelve micrometres.

What this paper adds to the related work

Building on the earlier contribution Groove-Assisted Solution Growth of Lead Bromide Perovskite Aligned Nanowires: A Simple Method towards Photoluminescent Materials with Guiding Light Properties, this paper advances the research line. This work uses the Fabry-Perot fringes of individual MAPbBr3 microcrystals as a source of quantitative information. A simultaneous fit of transmittance and photoluminescence retrieves crystal thickness and the real and imaginary parts of the refractive index near the band edge, while defining when a planar microcrystal behaves as an optical cavity.

Figure 2. SEM images of perovskite crystal morphologies
Journal article
ACS Omega 3, 5229-5236 (2018)
Single Crystal Growth of Hybrid Lead Bromide Perovskites Using a Spin-Coating Method
R. García-Aboal, R. Fenollosa, F. Ramiro-Manzano, I. Rodríguez, F. Meseguer and P. Atienzar

What the related paper adds

This earlier paper establishes a scientific basis for Optical Properties of Organic/Inorganic Perovskite Microcrystals through the Characterization of Fabry-Pérot Resonances. This study develops a fast spin-coating route to micrometre-sized MAPbBr3 single crystals and shows how rotation speed and coordinating additives control shape, orientation and defect density. The improved planar crystals are not only cleaner model specimens but also support optical resonances, providing the material platform used by later optical studies.

What this paper adds to the related work

Building on the earlier contribution Single Crystal Growth of Hybrid Lead Bromide Perovskites Using a Spin-Coating Method, this paper advances the research line. This work uses the Fabry-Perot fringes of individual MAPbBr3 microcrystals as a source of quantitative information. A simultaneous fit of transmittance and photoluminescence retrieves crystal thickness and the real and imaginary parts of the refractive index near the band edge, while defining when a planar microcrystal behaves as an optical cavity.

Research fields

Bottom-up

Solution-grown MAPbBr₃ microcrystals act simultaneously as the material under study and as naturally formed planar cavities. Their parallel crystal faces generate Fabry-Pérot resonances without adding a separately fabricated resonator.

Simulations & fits

Transmittance and photoluminescence are fitted together with analytical cavity models that include absorption, dispersion, sample thickness and the numerical aperture of the collection optics. This joint treatment extracts both parts of the refractive index around the electronic band edge.

Characterization

Angle-collecting microscope objectives record complementary transmission and emission spectra from the same microcrystal. Tracking how their resonance envelopes respond differently to numerical aperture provides an internal check on the fitted thickness and optical constants.

RESEARCH TOPICS

EmissionPhotoluminescence is not fitted as an isolated material band. Figure 4 shows that one refractive-index model can reproduce both signals from a 3.96 μm crystal, which is more restrictive than fitting either spectrum alone and helps distinguish cavity modulation from the intrinsic emission profile.InterferenceParallel crystal faces form a Fabry-Pérot cavity whose fringes depend on wavelength, thickness, absorption and collection angle. The analysis therefore treats interference visibility as a coupled geometrical and optical problem rather than a simple quality label.MaterialsThe method retrieves both real and imaginary parts of the refractive index from an individual hybrid perovskite microcrystal, avoiding the grain boundaries and orientational averaging of a polycrystalline film. This single-crystal approach exposes resonant behaviour that can disappear when many differently shaped grains contribute to a macroscopic spectrum.ResonatorsThe crystal itself is the resonator: no deposited mirrors are required because reflections at the glass-perovskite and perovskite-air interfaces provide optical feedback. The resulting model is also a design tool: it predicts which thickness and collection aperture will preserve useful cavity contrast in future perovskite microcavities.ChemistryMAPbBr3 microcrystals are grown from 1 M methylammonium bromide and 1 M lead bromide in DMF, using N-cyclohexyl-2-pyrrolidone as an additive, and spin-coated onto quartz at 800 rpm. The chemistry is therefore relevant not as a generic perovskite label but because solvent coordination, additive-assisted crystallisation and stoichiometry determine the morphology on which the Fabry-Pérot analysis depends.
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