低次元の層状ペロフスキットのブロードバンド可視光放射のための長寿命色センターの形成
Edward P Booker1, Tudor H Thomas1, Claudio Quarti2
1Cavendish Laboratory, University of Cambridge , CB3 0HE Cambridge, United Kingdom.
Journal of the American Chemical Society
|November 21, 2017
まとめ
ハイブリッド・ペロブスキットの ブロードバンド可視放射は 特定の結晶の方向性ではなく ヨウ化物の欠陥から発生します これらの欠陥を制御することは ホワイトライトエミッターの設計の鍵です
科学分野:
- 材料科学
- 凝縮物質物理学
- 固体化学
背景:
- 層状のハイブリッド鉛ハリドペロブスキットは,ユニークな光物理的性質を示しています.
- ブロードバンド可視放射は,いくつかのペロブスキート系で観察されていますが,その起源は完全に理解されていません.
- 新型光電子機器の開発には,放出メカニズムを理解することが不可欠です.
研究 の 目的:
- 001方向ヘキシラモニウム (HA) とドデチラモニウム (DA) 鉛ヨウ酸化ペロブスキートのブロードバンド可視放射の起源を調査する.
- 構造的および光物理的特徴と相関する.
- 低エネルギー放出における欠陥の役割を決定する.
主な方法:
- 第一原理密度関数理論 (DFT) のシミュレーション
- 時間解像度と安定状態の光発光スペクトロスコーピー
- 超高速吸収スペクトル
- 300Kから4KまでのX線 difraksion (XRD) 測定
主要な成果:
- HA2PbI4とDA2PbI4の両方の薄膜で200K以下で赤にシフトしたブロードバンド放射帯 (FWHM ~0.4 eV) が観察されました.
- このサブバンドギャップの放出の寿命は エクシトニク・トランジションより数桁長くなります
- XRDは,約200KのDA2PbI4の相変化を含む,温度に依存する八面形の傾きと格子間隔の変化を明らかにした.
- DFTシミュレーションでは,HA2PbI4における低エネルギー放出源として,インタースティシャルヨウ化物とフレンケル欠陥が特定されました.
結論:
- ブロードバンド白光放射は,2Dハイブリッドペロブスキットの一般的な特性であり,特定の方向性または組成に限定されません.
- 低エネルギー放出は欠陥,特にインタースティシャルヨウ素とフレンケル欠陥に起因する.
- 欠陥制御はペロブスキート材料の白光放出特性を調整するために不可欠です.
関連する概念動画
Emission Spectra
When solids, liquids, or condensed gases are heated sufficiently, they radiate some of the excess energy as light. Photons produced in this manner have a range of energies, and thereby produce a continuous spectrum in which an unbroken series of wavelengths is present.
UV–Vis Spectrum
When light passes through a substance, a portion of the light is absorbed while the remaining light is reflected or transmitted. If the molecule absorbs light between the wavelengths of 180–400 nm range, the UV spectrum is obtained, and if it absorbs light in the 400–780 nm wavelength range, the visible spectrum is obtained.
The UV–Vis spectrum of a molecule is the plot of its absorbance versus wavelength. The plot is drawn by taking molar absorptivity (ε) or log ε on the y-axis (ordinate)...
The UV–Vis spectrum of a molecule is the plot of its absorbance versus wavelength. The plot is drawn by taking molar absorptivity (ε) or log ε on the y-axis (ordinate)...
Total Internal Reflection Fluorescence Microscopy
Total internal reflection fluorescence microscopy or TIRF is an advanced microscopic technique used to visualize fluorophores in samples close to a solid surface with a higher refractive index, such as a glass coverslip. TIRF only allows fluorophores in proximity to the solid surface to be excited. When light from a medium with a lower refractive index (such as air) hits the glass coverslip at a critical angle, the light undergoes total internal reflection stead of passing through the glass.
Photoluminescence: Fluorescence and Phosphorescence
Photoluminescence is a process where a molecule absorbs light energy and re-emits it in the form of light. This phenomenon occurs when a substance absorbs photons, promoting its electrons to higher energy level excited states, followed by a relaxation process in which the electrons return to their original ground state energy levels and emit light. Photoluminescence is widely observed in various materials, including semiconductors, and organic and inorganic compounds.
A pair of electrons in a...
A pair of electrons in a...
Photoluminescence: Applications
Photoluminescence offers a wide range of applications due to its inherent sensitivity and selectivity. This technique allows for both direct and indirect analyses of the analyte. Direct quantitative analysis is possible when the analyte exhibits a favorable quantum yield for fluorescence or phosphorescence. However, an indirect analysis may be feasible if the analyte is not fluorescent or phosphorescent, or if the quantum yield is unfavorable. Indirect methods include reacting the analyte with...
Fluorescence and Phosphorescence: Instrumentation
Fluorometers and spectrofluorometers are two types of instruments used for measuring molecular fluorescence. These instruments differ in how they select excitation and emission wavelengths and the type of light sources they utilize. Fluorometers use absorption interference filters to choose excitation and emission wavelengths. The excitation source in a fluorometer is typically a low-pressure mercury vapor lamp that emits intense lines distributed throughout the ultraviolet and visible regions.


