Research

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8 pages, 1698 KiB

Open AccessArticle

External Electric Field Tailored Spatial Coherence of Random Lasing

by Yaoxing Bian, Hongyu Yuan, Junying Zhao, Dahe Liu, Wenping Gong and Zhaona Wang

Crystals 2022, 12(8), 1160; https://doi.org/10.3390/cryst12081160 - 18 Aug 2022

Cited by 5 | Viewed by 1327

In this study, spatial coherence tunable random lasing is proposed by designing a random laser with separate coupling configuration between the gain medium and the scattering part. By using the polymer dispersion liquid crystal (PDLC) film with tunable scattering coefficient for supplying random [...] Read more.

In this study, spatial coherence tunable random lasing is proposed by designing a random laser with separate coupling configuration between the gain medium and the scattering part. By using the polymer dispersion liquid crystal (PDLC) film with tunable scattering coefficient for supplying random scattering feedback and output modification, red, green and blue random lasers are obtained. By applying or removing electric field to manipulate the scattering intensity of the PDLC film, intensity and spatial coherence of these random lasing are then switched between the high or low state. This work demonstrates that controlling the external scattering intensity is an effective method to manipulate the spatial coherence of random lasing. Full article

(This article belongs to the Special Issue Organic Optoelectronics: Photoelectronic Conversion Materials, Physics and Devices)

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12 pages, 4354 KiB

Open AccessArticle

Narrowband Near-Infrared Perovskite/Organic Photodetector: TCAD Numerical Simulation

by Marwa S. Salem, Ahmed Shaker, Amal H. Al-Bagawia, Ghada Mohamed Aleid, Mohamed S. Othman, Mohammad T. Alshammari and Mostafa Fedawy

Crystals 2022, 12(8), 1033; https://doi.org/10.3390/cryst12081033 - 25 Jul 2022

Cited by 2 | Viewed by 2031

Abstract

Narrowband photodetectors (PD) established in the near-infrared (NIR) wavelength range are highly required in a variety of applications including high-quality bioimaging. In this simulation study, we propose a filter-less narrowband PD based on the architecture of perovskite/organic heterojunction. The most decisive part of [...] Read more.

Narrowband photodetectors (PD) established in the near-infrared (NIR) wavelength range are highly required in a variety of applications including high-quality bioimaging. In this simulation study, we propose a filter-less narrowband PD based on the architecture of perovskite/organic heterojunction. The most decisive part of the photodetector is the hierarchical configuration of a larger bandgap perovskite material with a thicker film followed by a lower bandgap organic material with a narrower layer. The design of the structure is carried out by TCAD numerical simulations. Our structure is based on an experimentally validated wideband organic PD, which is modified by invoking an additional perovskite layer having a tunable bandgap. The main detector device comprises of ITO/perovskite (Cs_yFA_1−yPb(I_xBr_1−x)₃)/organic blend (PBDTTT-c:C60-PCBM)/PEDOT:PSS/Al. The simulation results show that the proposed heterojunction PD achieves satisfactory performance when the thickness of perovskite and organic layers are 2.5 µm and 500 nm, respectively. The designed photodetector achieves a narrow spectral response at 730 nm with a full width at half-maximum (FWHM) of 33 nm in the detector, while having a responsivity of about 0.12 A/W at zero bias. The presented heterojunction perovskite/organic PD can efficiently detect light in the wavelength range of 700 to 900 nm. These simulation results can be employed to drive the development of filter-less narrowband NIR heterojunction PD. Full article

(This article belongs to the Special Issue Organic Optoelectronics: Photoelectronic Conversion Materials, Physics and Devices)

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10 pages, 1526 KiB

Open AccessArticle

Substrate Effects on the Random Lasing Performance of Solution-Processed Hybrid-Perovskite Multicrystal Film

by Jingyun Hu and Xinping Zhang

Crystals 2022, 12(3), 334; https://doi.org/10.3390/cryst12030334 - 27 Feb 2022

Cited by 1 | Viewed by 1967

Abstract

We report dependence of random lasing performance of directly spin-coated multicrystalline thin films of an organic–inorganic hybrid, halide perovskite CH₃NH₃PbBr₃ (MAPbBr₃), on different substrates. It was discovered that random lasing performance is strongly dependent on the [...] Read more.

We report dependence of random lasing performance of directly spin-coated multicrystalline thin films of an organic–inorganic hybrid, halide perovskite CH₃NH₃PbBr₃ (MAPbBr₃), on different substrates. It was discovered that random lasing performance is strongly dependent on the surface energy properties of the substrate, which determine the morphology and crystallization properties of the spin-coated film, and will consequently determine its optical scattering and emission properties. Using indium–tin oxide (ITO)-coated glass, fused silica, and tricyclo[5.2.1.0^2,6] decanedimethanol diacrylate (ADCP)-coated fused silica as the substrate materials, we compared the spectroscopic response of the random lasers and thus justified the photophysical mechanisms involved. The modification of the surface properties of the substrate enables controlling of the MAPbBr₃ crystallization and leads to the changing of the random lasing properties. The discoveries herein are also important for the construction of other types of laser devices, where the substrate effects should be considered during the design and preparation of the micro-/nano structures. Full article

(This article belongs to the Special Issue Organic Optoelectronics: Photoelectronic Conversion Materials, Physics and Devices)

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9 pages, 2047 KiB

Open AccessArticle

Photodetector Based on CsPbBr₃/Cs₄PbBr₆ Composite Nanocrystals with High Detectivity

by Yue Han, Rong Wen, Feng Zhang, Linlin Shi, Wenyan Wang, Ting Ji, Guohui Li, Yuying Hao, Lin Feng and Yanxia Cui

Crystals 2021, 11(11), 1287; https://doi.org/10.3390/cryst11111287 - 24 Oct 2021

Cited by 3 | Viewed by 2222

Abstract

High-quality, all-inorganic CsPbBr₃/Cs₄PbBr₆ composite perovskite nanocrystals (NCs) were obtained with all-solution-processing at room temperature, and a photodetector (PD) with high detectivity was realized based on CsPbBr₃/Cs₄PbBr₆ NCs. The detectivity (D*) of [...] Read more.

High-quality, all-inorganic CsPbBr₃/Cs₄PbBr₆ composite perovskite nanocrystals (NCs) were obtained with all-solution-processing at room temperature, and a photodetector (PD) with high detectivity was realized based on CsPbBr₃/Cs₄PbBr₆ NCs. The detectivity (D*) of the proposed PD is 4.24 × 10¹² Jones under 532 nm illumination, which is among the highest levels for PDs based on all-inorganic perovskite NCs. In addition, a high linear dynamic range (LDR) of 115 dB under 1 V bias was also realized. Furthermore, the underlying mechanism for the enhanced performance of the proposed PD was discussed. Our work might promote the preparation of high-performance PDs based on dual-phase all-inorganic perovskite nanocrystals. Full article

(This article belongs to the Special Issue Organic Optoelectronics: Photoelectronic Conversion Materials, Physics and Devices)

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10 pages, 2766 KiB

Open AccessArticle

Two-Dimensional Crystalline Gridding Networks of Hybrid Halide Perovskite for Random Lasing

by Jingyun Hu, Haibin Xue and Xinping Zhang

Crystals 2021, 11(9), 1114; https://doi.org/10.3390/cryst11091114 - 13 Sep 2021

Cited by 4 | Viewed by 1721

Abstract

We report fabrication of large-scale homogeneous crystallization of CH₃NH₃PbBr₃ (MAPbBr₃) in the patterned substrate by a two-dimensional (2D) grating. This achieves high-quality optotelectronic structures on local sites in the micron scales and a homogeneous thin-film device [...] Read more.

We report fabrication of large-scale homogeneous crystallization of CH₃NH₃PbBr₃ (MAPbBr₃) in the patterned substrate by a two-dimensional (2D) grating. This achieves high-quality optotelectronic structures on local sites in the micron scales and a homogeneous thin-film device in a centimeter scale, proposing a convenient technique to overcome the challenge for producing large-area thin-film devices with high quality by spin-coating. Through matching the concentration of the MAPbBr₃/DMF solutions with the periods of the patterning structures, we found an optimized size of the patterning channels for a specified solution concentration (e.g., channel width of 5 μm for a concentration of 0.14 mg/mL). Such a design is also an excellent scheme for random lasing, since the crystalline periodic networks of MAPbBr₃ grids are multi-crystalline constructions, and supply strong light-scattering interfaces. Using the random lasing performance, we can also justify the crystallization qualities and reveal the responsible mechanisms. This is important for the design of large-scale optoelectronic devices based on thin-film hybrid halide perovskites. Full article

(This article belongs to the Special Issue Organic Optoelectronics: Photoelectronic Conversion Materials, Physics and Devices)

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8 pages, 2362 KiB

Open AccessArticle

Mobility of Small Molecules in Solid Polymer Film for π-Stacked Crystallization

by Yue Liu and Xinping Zhang

Crystals 2021, 11(9), 1022; https://doi.org/10.3390/cryst11091022 - 25 Aug 2021

Cited by 1 | Viewed by 1676

Abstract

Crystallization or π-stacked aggregation of small molecules is an extensively observed phenomenon which favors charge transport along the crystal axis and is important for the design of organic optoelectronic devices. Such a process has been reported for N,N′-Bis(1-ethylpropyl)-3,4,9,10-perylenebis(dicarboximide) (EPPTC). However, [...] Read more.

Crystallization or π-stacked aggregation of small molecules is an extensively observed phenomenon which favors charge transport along the crystal axis and is important for the design of organic optoelectronic devices. Such a process has been reported for N,N′-Bis(1-ethylpropyl)-3,4,9,10-perylenebis(dicarboximide) (EPPTC). However, the π-stacking mechanism requires solution–air or solution–solid interfaces. The crystallization or aggregation of molecules doped in solid films is generally thought to be impossible, since the solid environment surrounding the small molecules does not allow them to aggregate together into π-stacked crystals. In this work, we demonstrate that the movement of the EPPTC molecules becomes possible in a solid polymer film when it is heated to above the glass transition temperature of the polymer. Thus, crystal particles can be produced as a doped matrix in a thin solid film. The crystallization process is found to be strongly dependent on the annealing temperature and the annealing time. Both the microscopic and spectroscopic evaluations verify such discoveries and characterize the related properties of these crystals. Full article

(This article belongs to the Special Issue Organic Optoelectronics: Photoelectronic Conversion Materials, Physics and Devices)

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14 pages, 3039 KiB

Open AccessArticle

High-Performance Flexible Transparent Electrodes Fabricated via Laser Nano-Welding of Silver Nanowires

by Tao Wang, Yinzhou Yan, Liye Zhu, Qian Li, Jing He, Xiaoxia Zhang, Xi Li, Xiaohua Zhang, Yongman Pan and Yue Wang

Crystals 2021, 11(8), 996; https://doi.org/10.3390/cryst11080996 - 21 Aug 2021

Cited by 2 | Viewed by 2440

Abstract

Silver nanowires (Ag-NWs), which possess a high aspect ratio with superior electrical conductivity and transmittance, show great promise as flexible transparent electrodes (FTEs) for future electronics. Unfortunately, the fabrication of Ag-NW conductive networks with low conductivity and high transmittance is a major challenge [...] Read more.

Silver nanowires (Ag-NWs), which possess a high aspect ratio with superior electrical conductivity and transmittance, show great promise as flexible transparent electrodes (FTEs) for future electronics. Unfortunately, the fabrication of Ag-NW conductive networks with low conductivity and high transmittance is a major challenge due to the ohmic contact resistance between Ag-NWs. Here we report a facile method of fabricating high-performance Ag-NW electrodes on flexible substrates. A 532 nm nanosecond pulsed laser is employed to nano-weld the Ag-NW junctions through the energy confinement caused by localized surface plasmon resonance, reducing the sheet resistance and connecting the junctions with the substrate. Additionally, the thermal effect of the pulsed laser on organic substrates can be ignored due to the low energy input and high transparency of the substrate. The fabricated FTEs demonstrate a high transmittance (up to 85.9%) in the visible band, a low sheet resistance of 11.3 Ω/sq, high flexibility and strong durability. The applications of FTEs to 2D materials and LEDs are also explored. The present work points toward a promising new method for fabricating high-performance FTEs for future wearable electronic and optoelectronic devices. Full article

(This article belongs to the Special Issue Organic Optoelectronics: Photoelectronic Conversion Materials, Physics and Devices)

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8 pages, 2088 KiB

Open AccessArticle

Vortex Laser Based on a Plasmonic Ring Cavity

by Xingyuan Wang, Xiaoyong Hu and Tianrui Zhai

Crystals 2021, 11(8), 901; https://doi.org/10.3390/cryst11080901 - 31 Jul 2021

Viewed by 1760

Abstract

The orbital angular momentum (OAM) of the structure light is viewed as a candidate for enhancing the capacity of information processing. Microring has advantages in realizing the compact lasers required for on-chip applications. However, as the clockwise and counterclockwise whispering gallery modes (WGM) [...] Read more.

The orbital angular momentum (OAM) of the structure light is viewed as a candidate for enhancing the capacity of information processing. Microring has advantages in realizing the compact lasers required for on-chip applications. However, as the clockwise and counterclockwise whispering gallery modes (WGM) appear simultaneously, the emitted light from the normal microring does not possess net OAM. Here, we propose an OAM laser based on the standing-wave WGMs containing clockwise and counterclockwise WGM components. Due to the inhomogeneous intensity distribution of the standing-wave WGM, the single-mode lasing for the OAM light can be realized. Besides, the OAM of the emitted light can be designed on demand. The principle and properties of the proposed laser are demonstrated by numerical simulations. This work paves the way for exploring a single-mode OAM laser based on the plasmonic standing-wave WGMs at the microscale, which can be served as a basic building block for on-chip optical devices. Full article

(This article belongs to the Special Issue Organic Optoelectronics: Photoelectronic Conversion Materials, Physics and Devices)

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10 pages, 1400 KiB

Open AccessArticle

A Theoretical Model of Quasicrystal Resonators: A Guided Optimization Approach

by Libin Cui, Anwer Hayat, Linzheng Lv, Zhiyang Xu and Tianrui Zhai

Crystals 2021, 11(7), 749; https://doi.org/10.3390/cryst11070749 - 26 Jun 2021

Cited by 2 | Viewed by 1262

Abstract

Fibonacci-spaced defect resonators were analytically investigated by cavity coupling, which exhibited a series of well-defined optical modes in fractals. The analytic model can be used to predict the output performance of microcavity lasers based on Fibonacci-spaced defect resonators, such as the mode number, [...] Read more.

Fibonacci-spaced defect resonators were analytically investigated by cavity coupling, which exhibited a series of well-defined optical modes in fractals. The analytic model can be used to predict the output performance of microcavity lasers based on Fibonacci-spaced defect resonators, such as the mode number, resonant frequency, and Q factor. All results obtained by the analytical solution are in good consistency with that obtained by the finite-difference time-domain method. The simulation result shows that the Q factor of the resonant modes would increase dramatically with the appearance of narrower optical modes. The proposed theoretical model can be used to inversely design high performance polymer lasers based on the Fibonacci-spaced defect resonators. Full article

(This article belongs to the Special Issue Organic Optoelectronics: Photoelectronic Conversion Materials, Physics and Devices)

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Review

Jump to: Research

24 pages, 4966 KiB

Open AccessReview

Review on Y6-Based Semiconductor Materials and Their Future Development via Machine Learning

by Sijing Zhong, Boon Kar Yap, Zhiming Zhong and Lei Ying

Crystals 2022, 12(2), 168; https://doi.org/10.3390/cryst12020168 - 24 Jan 2022

Cited by 20 | Viewed by 6534

Abstract

Non-fullerene acceptors are promising to achieve high efficiency in organic solar cells (OSCs). Y6-based acceptors, one group of new n-type semiconductors, have triggered tremendous attention when they reported a power-conversion efficiency (PCE) of 15.7% in 2019. After that, scientists are trying to improve [...] Read more.

Non-fullerene acceptors are promising to achieve high efficiency in organic solar cells (OSCs). Y6-based acceptors, one group of new n-type semiconductors, have triggered tremendous attention when they reported a power-conversion efficiency (PCE) of 15.7% in 2019. After that, scientists are trying to improve the efficiency in different aspects including choosing new donors, tuning Y6 structures, and device engineering. In this review, we first summarize the properties of Y6 materials and the seven critical methods modifying the Y6 structure to improve the PCEs developed in the latest three years as well as the basic principles and parameters of OSCs. Finally, the authors would share perspectives on possibilities, necessities, challenges, and potential applications for designing multifunctional organic device with desired performances via machine learning. Full article

(This article belongs to the Special Issue Organic Optoelectronics: Photoelectronic Conversion Materials, Physics and Devices)

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