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Structural phase transition causing anomalous photoluminescence behavior in perovskite (C6H11NH3)2[PbI4]
A Yangui1, S Pillet2, A Mlayah3
1Groupe d'Etudes de la Matière Condensée, UMR CNRS 8653-Université de Versailles Saint Quentin En Yvelines, 45 Avenue des Etats-Unis, 78035 Versailles, France.
The Journal of Chemical Physics
|December 17, 2015
Summary
This study investigates the optical and structural properties of (C6H11NH3)2[PbI4] hybrid perovskites. Temperature-dependent measurements reveal phase transitions linked to exciton behavior and band gap modulation, crucial for optoelectronic device design.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Solid-State Chemistry
Background:
- Organic-inorganic hybrid perovskites exhibit unique optoelectronic properties.
- Understanding structure-property relationships is key for developing advanced materials.
- Exciton dynamics and phase transitions significantly influence material performance.
Purpose of the Study:
- To investigate the optical and structural characteristics of (C6H11NH3)2[PbI4] (C6PbI4).
- To correlate temperature-dependent photoluminescence (PL) and X-ray diffraction (XRD) data.
- To elucidate the mechanisms behind observed optical anomalies and structural transitions.
Main Methods:
- Optical absorption and photoluminescence (PL) spectroscopy at various temperatures.
- X-ray diffraction (XRD) on powder and single crystals as a function of temperature.
- Analysis of exciton binding energy and emission band characteristics.
Main Results:
- Observed absorption bands at 2.44 and 3.21 eV; PL peaks at 2.41 eV (free excitons) and 2.24 eV (localized excitons).
- Identified low-temperature emission bands (P3, LB) and anomalous thermal dependence of PL spectra at 40 K and 130 K.
- Discovered significant changes in interlayer spacing at 50 K and ~138 K, including a commensurate-to-incommensurate structural phase transition around 138 K.
Conclusions:
- The structural phase transition involving PbI6 octahedron distortion modulates the band gap, explaining the emergence of the LB and anomalous P1 behavior.
- Changes in interlayer spacing correlate with variations in P2 intensity and LB emission.
- The intricate interplay between structural and optical properties in C6PbI4 highlights its potential for tailored optoelectronic device applications.
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