Clabel H J L, Awan Iram T, Lozano G, Pereira-da-Silva M A, Romano R A, Rivera V A G, Ferreira S O, Marega E
Physics Institute of São Carlos, University of São Paulo, P.O. Box 369, 13560-970, São Carlos, SP, Brazil.
Facultad de Ciencias Físicas, Universidad Nacional Mayor de San Marcos, UNMSM, Lima, Lima, Peru.
Phys Chem Chem Phys. 2020 Jul 8;22(26):15022-15034. doi: 10.1039/d0cp01010c.
Photonic and electronic properties exist inherently in ferroelectric barium titanate (BaTiO3); severe luminescence quenching also exists due to the insufficient confinement of excitons. In this sense, high optical emission can only be achieved by its chemical and structural modification. Thin BaTiO3 and Er:BaTiO3 films were grown by the spin coating method on a glass substrate at room temperature. Self-trapping of excitons in the thin BaTiO3 film and its structural modification due to the doping with Er3+ ions (Er:BaTiO3) are verified using scanning confocal fluorescence microscopy (SCFM), where self-trapping excitons never occured in its pure state. By thermal treatment and doping (BaTiO3 and Er:BaTiO3) we obtained localization of the excitons, which would further induce lattice strain around the surface defects, to accommodate the self-trapped excitons. With such a self-trapped state, the structure of BaTiO3 generates broadband emission of several overlapping bands between 1.95 and 2.65 eV at room temperature, while the structure Er:BaTiO3 showed defined emission bands at 2.24 and 2.35 eV, with very weak contributions of the emission due to the self-trapping state. The influence of the variation of the excitation wavelength using 1PE and 2PE on the emission bands of BaTiO3 and Er:BaTiO3 is also investigated. The results of enhanced emission bands suggest a clear dependence of the emission intensity on the excitation energy, where a ∼3 fold enhancement in emission has been demonstrated under Er3+ (1.55 eV) excitation, which can be attributed to effective energy transfer between the Er3+ ions. As a result, it is concluded that the developed BaTiO3 and Er:BaTiO3 can pave the way for future photonic devices.
铁电钛酸钡（BaTiO3）本身具有光子和电子特性；由于激子限制不足，还存在严重的发光猝灭现象。从这个意义上说，只有通过其化学和结构改性才能实现高光学发射。采用旋涂法在室温下于玻璃基板上生长了BaTiO3薄膜和Er:BaTiO3薄膜。利用扫描共焦荧光显微镜（SCFM）验证了BaTiO3薄膜中激子的自陷及其因掺杂Er3+离子（Er:BaTiO3）而发生的结构改性，其中自陷激子从未以其纯态出现。通过热处理和掺杂（BaTiO3和Er:BaTiO3），我们获得了激子的局域化，这将进一步在表面缺陷周围诱导晶格应变，以容纳自陷激子。处于这种自陷状态时，BaTiO3的结构在室温下产生1.95至2.65 eV之间几个重叠带的宽带发射，而Er:BaTiO3的结构在2.24和2.35 eV处显示出明确的发射带，自陷态发射的贡献非常微弱。还研究了使用单光子激发（1PE）和双光子激发（2PE）时激发波长变化对BaTiO3和Er:BaTiO3发射带的影响。发射带增强的结果表明发射强度明显依赖于激发能量，其中在Er3+（1.55 eV）激发下发射增强了约3倍，这可归因于Er3+离子之间的有效能量转移。结果得出结论，所开发的BaTiO3和Er:BaTiO3可为未来的光子器件铺平道路。
