Fabrication of low dimensional anisotropic semiconductor structures is essential for the development of polarization-sensitive optoelectronic devices, display and low power light source devices. However, unlike light intensity and color that are transformed into perceptual quantities of brightness and hue, making use of light polarization information is still challenging. Recently, research group of Qing Zhang, from the College of Engineering, Peking University made new progresses in strong emission anisotropy of one dimensional perovskite nanowire arrays and its size-dependent polarization. Related works have been published online at Adv. Mater. 2018, 1801805, the title is “Ultrathin CsPbX3Nanowire Arrays with Strong Emission Anisotropy”. The first affiliation is Peking University.
Zhang’s group firstly have demonstrated the fabrication of CsPbBr3 and CsPbCl3 nanowires with thickness down to 15 and 7 nm using chemical vapor phased deposition. Combined confocal fluorescence microspectroscopy, strong emission anisotropy of perovskite nanowire arrays and its relevant size-dependent polarization were reported. The polarization ratio up to ≈ 0.78 is demonstrated in the nanowires with thickness T < 40 nm due to the electrostatic dielectric confinement. With the increasing of thickness, the polarization ratio remarkably reduces monotonously to ≈ 0.17 until T ≈ 140 nm; and further oscillates in a small amplitude owing to the wave characteristic of light as T > 140 nm. The research has demonstrated that the three interaction regimes are mainly owing to electrostatic mismatch, rising of wave characteristic and waveguide modes competition, respectively.
The findings not only constitute a significant step forward polarization-sensitive perovskite optoelectronic devices, but also advance fundamental understanding of their polarization properties of perovskite nanowires.
Figure a. Polarization measurement configuration of CsPbX3 nanowires. b. Optical PL images of 15-nm-thick CsPbBr3 nanowires at different polarization directions (0°, 30°, 60°, 90°). c. Scaling law of polarization ratio of CsPbBr3 nanowires with different thickness.
This work was collaborated with Prof. Xina Wang at Hubei University, Prof. Xinfeng Liu at the National Center for Nanoscience and Technology, Prof. Yanfeng Zhang at the College of Engineering of Peking University, Prof. Peng Gao at the school of Physics of Peking University. The research is supported by the National Key Research and Development Program and the State Key Laboratory of Low Dimensional Quantum Physics of Tsinghua University.