Out-of-plane orientated self-trapped excitons enabled polarized light guiding in 2D perovskites

Active optical waveguides combine light source and waveguides together in an individual component, which are essential for the integrated photonic chips. Although 1D luminescent materials based optical waveguides were extensively investigated, 2D waveguides allow photons to flow within a plane and serve as an ideal component for the ultracompact photonic circuits. Nevertheless, light guiding in 2D planar structures normally relies on the precise control of molecular orientation, which is complicated and low yield. Here, we report a strategy to guide polarized light in 2D microflakes by making use of the out-of-plane (OP) orientation of self-trapped excitons in as-synthesized 2D perovskite microplates. A space confined crystallization method is developed to synthesize 2D perovskite microflakes with dominated broad self-trapped excitons emission at room temperature, which are highly OP orientated with a percentage of the OP component over 85%. Taking advantages of the negligible absorption coefficient and improved coupling efficiency of OP orientated self-trapped exciton emission to the planar waveguide mode of the as-synthesized perovskite microflakes, we have achieved a broadband polarized light guiding with a full width at half maximum over 120 nm. Our findings provide a promising platform for the development of ultracompact photonic circuits

Controllable Synthesis of Two-Dimensional Ruddlesden–Popper-Type Perovskite Heterostructures

Two-dimensional Ruddlesden–Popper type perovskites (2D perovskites) have recently attracted increasing attention. It is expected that 2D perovskite-based heterostructures can significantly improve the efficiency of the optoelectronic devices and extend the material functionalities; however, rational synthesis of such heterostructures has not been realized to date. We report on a general low-temperature synthetic strategy for the synthesis of 2D perovskite-based lateral and vertical (<i>n</i>-CH₃(CH₂)₃NH₃)₂PbI₄/(<i>n</i>-CH₃(CH₂)₃NH₃)₂(CH₃NH₃)­Pb₂I₇ heterostructures for the first time. A combination of solution synthesis and gas–solid phase intercalation approach allows us to efficiently synthesize both lateral and vertical heterostructures with great flexibility. X-ray diffraction, photoluminescence, and photoluminescence excitation mapping and electrical transport measurement studies reveal the successful synthesis of lateral and vertical heterostructures with precisely spatial-modulation control and distinguishable interfaces. Our studies not only provide an efficient synthetic strategy with great flexibility, enabling us to create 2D perovskite-based heterostructures, but also offer a platform to investigate the physical processes in those heterostructures

Two-Step Growth of 2D Organic–Inorganic Perovskite Microplates and Arrays for Functional Optoelectronics

Two-dimensional (2D) perovskites have recently attracted intensive interest for their great stability against moisture, oxygen, and illumination compared with their three-dimensional (3D) counterparts. However, their incompatibility with a typical lithography process makes it difficult to fabricate integrated device arrays and extract basic optical and electronic parameters from individual devices. Here, we develop a combination of solution synthesis and a gas–solid-phase intercalation strategy to achieve hexagonal-shaped 2D perovskite microplates and arrays for functional optoelectronics. The 2D perovskite microplates were achieved by first synthesizing the lead iodide (PbI₂) microplates from an aqueous solution and then following with intercalation via the vapor transport method. This method further allows us to synthesize arrays of 2D perovskite microplates and create individual 2D perovskite microplate-based photodetectors. In particular, chlorine (Cl) can be efficiently incorporated into the microplates, resulting in significantly improved performance of the 2D perovskite microplate-based photodetectors

Flexibly and Repeatedly Modulating Lasing Wavelengths in a Single Core–Shell Semiconductor Microrod

Modulating lasing wavelength flexibly and repeatedly on a single rod is essential to the practical applications of micro/nanorod lasers. In this paper, a structure that decouples the gain medium and optical cavity is proposed, where the corresponding mechanism for the lasing wavelength shift is explained. Based on the above structure, one kind of wavelength continuously variable lasers is achieved on a single GaN/InGaN core–shell microrod without modifying the geometry of the resonant cavity or cutting the microrod. By using this method, lasing wavelength can be modulated from 372 to 408 nm flexibly and repeatedly in a 10 μm facilely synthesized microrod. This approach demonstrates a big application potential in numerous fields consisting of optical telecommunication and environmental monitoring