Summary of Research Progress: Academician Huang Wei and his research team

Biography

Published research results:

1. Thesis: Dynamic Resonant Organic Long Afterglow Materials

Academician Huang Wei and Prof. Runfeng Chen from Nanjing University of Posts and Telecommunications(Communications), after the first report of organic long afterglow materials ( Nat. Mater. 2015 , 14 , 685) in 2015 , took advantage of the unique dynamic adaptability of resonant structures to effectively Adjust its own structure to achieve the control of the ground state, excited state energy levels and transition components of the material. Two new types of long afterglow materials with NP = O / NP = S structure have been developed. Theoretical calculations show that compared with molecules with NP structure, molecules based on the NP = O / NP = S resonance structure have adjustable singlet-triplet energy levels, which can effectively reduce real-time singlet-triplet states. State energy level difference (Real-time Δ E ST ) and dynamically adjustable transition components, so it has more intersystem crossing channels and significantly enhanced self-selected orbit coupling effects, which can effectively promote intersystem crossing (Intersystem Crossing, ISC), thereby obtaining a high triplet exciton concentration. Secondly, the relatively flat conjugate structure introduced in the molecule is used to construct effective H-aggregates, stabilize highly active triplet excitons, and then achieve high afterglow luminous efficiency and long luminous lifetime. The longest life of the developed afterglow material is 0.67 s, the intersystem crossing rate is as high as 10 ⁷ s ^-1 , and the luminous efficiency is 4.0%. This result breaks the contradiction that the life and efficiency of the afterglow material cannot be improved at the same time. This result was recently published on Advanced Materials (10.1002 / adma.201803856) and was selected as the current inner cover. The first author of the article is Tao Ye, a PhD graduate of Nanjing University of Posts and Telecommunications.

Article link: https://onlinelibrary.wiley.com/doi/abs/10.1002/adma.201803856

2. Thesis: Oriented quasi-two-dimensional perovskite for high-performance optoelectronic devices

Academician Huang Wei of Nanjing University of Technology and Professor Wang Jianpu (co-corresponding author) haveused 3-bromobenzylamine iodide (3BBAI) to prepare a highly efficient and water-stable quasi-two-dimensional perovskite solar cell with a power conversion efficiency (PCE) It reached 18.20%, and published a research paper entitled " Oriented Quasi-2D Perovskites for High Performance Optoelectronic Devices " on Adv. Mater. The PhD students Yang Rong and associate researcher Li Renzhi were the co-first authors. After the unpackaged device is left for 2400 h in an atmospheric environment with a relative humidity of 40%, the efficiency still maintains more than 82% of the initial value, and the photovoltaic parameters are almost unchanged after being immersed in water for 60 s. The superior performance of perovskite solar cells should be attributed to quasi-two-dimensional perovskite thin films with hydrophobicity, high electronic order, and high crystallinity. The upper layer of the film is a highly oriented three-dimensional perovskite component. Its small band gap and low exciton binding energy can achieve low-energy solar photon utilization and efficient charge separation, while the bottom of the film is a vertically-growing wide-band gap calcium. The titanium ore composition is conducive to achieving efficient charge transfer. In addition, due to the suppression of non-radiative recombination, the device can also work well as a light emitting diode (LED), up to 3.85%. In the atmospheric environment, the unpackaged device has a working life of about 96 h at a high current density of 200 mA · cm ^-2 .

Literature link: Oriented Quasi-2D Perovskites for High Performance Optoelectronic Devices ( Adv. Mater. , 2018, DOI: 10.1002 / adma.201804771)

3. Thesis: Perovskite LEDs based on spontaneously formed sub-micron structure

Academician Huang Wei from Nanjing University of Technology (currently Northwestern Polytechnical University) and Professor Wang Jianpu (co-corresponding author) teamed up with Zhejiang University , Nanjing University of Posts and Telecommunications, and Northwestern Polytechnical University to demonstrate the efficiency of solution-processed perovskite And high-brightness electroluminescence, spontaneously forms a sub-micron structure, which can effectively extract light from the device and maintain electroluminescence regardless of wavelength and viewing angle. These perovskites are formed by adding amino acid additives to the perovskite precursor solution. In addition, additives can effectively passivate the surface defects of perovskite and reduce non-radiative recombination. Perovskite LED has a peak external quantum efficiency of 20.7% (current density of 18mA / cm & lt ² ), the energy conversion efficiency of 12% (at 10mA / cm & lt ² at a high current density), the organic LED performance close to the optimum value . Related results were published in Nature under the title " Perovskite light-emitting diodes based on spontaneously formed submicrometre-scale structures " .

Literature link : Perovskite light-emitting diodes based on spontaneously formed submicrometre-scale structures (Nature, 2018, DOI: 10.1038 / s41586-018-0576-2)

4. Thesis: Enhancement of Luminous Efficiency and Phosphorescence Lifetime of Ultra-long Organic Phosphorescent Materials through Molecular Self-Assembly

Academician Huang Wei of Nanjing University of Technology and Prof. An Zhongfu (common communication) prepared ultra-long organic phosphorescent materials through self-assembly of melamine and aromatic carboxyl groups in aqueous solution. Through the supramolecular framework formed by various intermolecular interactions, a highly rigid three-dimensional network can be constructed to fix the atoms therein, which effectively reduces the non-radiative transition of the triplet electrons and promotes intersystem crossing. The obtained supramolecular organic framework can achieve a luminous lifetime of up to 1.91 seconds and a phosphorescent quantum efficiency of 24.3%. The work was published in J. Am. Chem. Soc. Under the title " Simultaneously Enhancing Efficiency and Lifetime of Ultralong Organic Phosphorescence Materials by Molecular Self-assembly " .

Literature link:

Simultaneously Enhancing Efficiency and Lifetime of Ultralong Organic Phosphorescence Materials by Molecular Self-assembly

(J. Am. Chem. Soc., 2018, DOI: 10. 1021 / jacs.8b03867)

5. Thesis: New Progress in Electroluminescence of Lead Halide Perovskites

Professor Cen Zijian Nanyang Technological University and Professor Huang Wei Nanjing University of Technology (co-author) recently published a report entitled Transcending the slow bimolecular recombination in lead- halide perovskites for electroluminescence article in NATURE COMMUNICATIONS, report them in Lead halide Recent advances in perovskites. The light-emitting efficiency bottleneck of conventional metal halide perovskite materials in light-emitting diodes is clearly illustrated from the perspective of microscopic carrier dynamics. Through the study of femtosecond ultrafast spectroscopy, it is proposed how to overcome the bottleneck in this mechanism by regulating the dimensions of perovskite, so as to achieve a high efficiency perovskite light-emitting diode. The research results lay a theoretical foundation for realizing a new type of perovskite light-emitting diode with high efficiency and low cost.

Original link: Transcending the slow bimolecular recombination in lead-halide perovskites for electroluminescence (Nat. Commun., 2017, Doi: 10.1038 / ncomms14558)

6. Thesis: Construction of hydrogen-bonded organic aromatic framework through π-π interaction in the molecular layer for obtaining ultra-long phosphorescence

Academician Huang Wei of Nanjing University of Technology and the research team of An Zhongfu successfully constructed hydrogen-bonded organic aromatic skeletons (HOAFs) with different pore diameters by dividing the inner sub-layer π-π interaction. For the first time, the prepared HOAFs achieved ultra-long organic phosphorescence in room temperature air, that is, organic long afterglow. Among them, the yellow fluorescence lifetime of PhTCz-1 reaches 79.8 ms, and afterglow emission can be observed for several seconds after stopping excitation. PhTCz-2 and PhTCz-3, due to the quenching effect of oxygen, their long afterglow phenomenon can only be observed in nitrogen, in view of this characteristic can be used to detect oxygen. This work extends the system of metal-free organic phosphorescent materials. At the same time, this new type of HOAFS material also has a high thermal decomposition temperature, which also provides new ideas for the design of new high-temperature stable HOFs. The result was published on Angew. Chem. Int. Ed. As " Hydrogen-Bonded Organic Aromatic Frameworks for Ultralong Phosphorescence by Intralayer π-π Interactions " .

Literature link: Hydrogen-Bonded Organic Aromatic Frameworks for Ultralong Phosphorescence by Intralayer π-π Interactions. (Angew. Chem. Int. Ed., 2018, DOI: 10.1002 / anie.201800697)

7. Thesis: Study on Reactive Metal Ligand Complexes in Multicolor Inkjet Reusable Paper

Huang Fellow Northwestern Polytechnical University , Professor Zhao Qiang of Nanjing University of Posts and Telecommunications ( co-corresponding author ) in Nat. Commun. Delivered a speech entitled "the Dynamic Metal-ligand Coordination for MULTICOLOUR and the Jet Water-Rewritable Pape r" article. The research and discussion on how to use the reversibility of dynamic metal ligand interactions to achieve the preparation of rewritable paper has broken the current limitations. The coating of polymer films containing terpyridine ligands on filter paper was studied. Multi-color images can be repeatedly coated with different metal salt solutions (MSAS) as inks that can coordinate with the ligands. Pictures can be retained for more than 6 months, and metal-ligand coordination can be easily erased with tetrabutylammonium fluoride (TBAF). By introducing a water-responsive light-emitting zinc complex into the imaging layer, another rewritable paper that can record information by using pure water as ink was developed. Water is a green resource, so water-jet rewritable paper was developed Significantly, this application will be a promising way to achieve multicolor waterjet printing with long retention times.

Literature link: Dynamic metal-ligand coordination for multicolour and water-jet rewritable paper (Nat. Commun., 2017, DOI: 10.1038 / s41467-017-02452-w)

8. Thesis: Non-post-treatment, non-doped diarylfluorene-based nanomolecules as hole transport materials for flexible pin-type perovskite solar cells

Professor Huang Wei ( corresponding author ) of Nanjing University of Technology and others published an article entitled " Diarylfluorene-based Nano-molecules as Dopant-Free Hole-transporting Materials without Post-treatment Process for Flexible Pin Type Perovskite Solar Cells " on Nano Energy . The research team designed two sets of diarylfluorene HTMs, with TPA or 9-NPC as the chain arms, and C8 or C6Cz as the side chains, which were named MC8-TPA, MC8-9-NPC, MC6Cz-TPA, and MC6Cz-9- NPC. These materials have good solubility in common organic solvents, and the spin-coated films have smooth interfaces and good hydrophobicity. They show complete crystalline state without subsequent heat treatment on ITO. The perovskite thin film prepared on diarylfluorene-based HTM is larger than that on PEDOT: PSS, about 300 nm. The maximum efficiency of the device is 13.85%, and the maximum efficiency of the flexible perovskite battery is 9.09%.

Literature link: Diarylfluorene-based Nano-molecules as Dopant-Free Hole-transporting Materials without Post-treatment Process for Flexible pin Type Perovskite Solar Cells (Nano Energy, 2017, DIO: 10.1016 / j.nanoen.2018.01.005)

9. Thesis: Two-dimensional flexible display with water energy

Academician Huang Wei of Nanjing University of Technology , Professor Meng Hong of Shenzhen Research Institute of Peking University, and Professor Ray H. Baughman of the University of Texas at Dallas (co-corresponding author does not distinguish the order) have studied a flexible display based on polarized electrode bridge A long-distance sensor using optical signals was constructed. The study was published in Advanced Materials under the title "Polar-Electrode-Bridged Electroluminescent Displays: 2D Sensors Remotely Communicating Optically" . Researchers have designed a light-emitting device with a new structure, which is mainly composed of four parts: a pair of electrodes stacked in parallel or side by side, a light-emitting layer, a dielectric layer, and a controllable electrode layer. By selecting different polarizing materials or conductive films, the controllability of the electrode layer is achieved. This new structure is not only simple, but also conducive to large-scale manufacturing. More importantly, compared with traditional light-emitting devices, a pair of opposite electrodes are no longer stacked on each other, but are arranged side by side. Because of this structural advantage, researchers have designed different types of devices. For example, when this flexible material is installed on an umbrella, when the water falls on the umbrella, the umbrella will emit light, which also makes it possible to build a remote detector that uses light signal changes.

Literature link: Polar-Electrode-Bridged Electroluminescent Displays: 2D Sensors Remotely Communicating Optically (Adv. Mater., 2017, DOI: 10.1002 / adma.201703552)

10. Thesis: Ultra-long organic phosphorescence excited by visible light by regulating intermolecular interactions

Academician Huang Wei of Nanjing University of Technology and researcher An Zhongfu (co-corresponding author) use concise chemical methods to obtain bright UOP by adjusting molecular sequences in solids exposed to visible light, such as mobile phone flashlights. The intermolecular interaction is regulated by the incorporation of halogen atoms, and the excitation spectrum shows a significant red shift. U-aggregated UOP has a high phosphorescent efficiency of 8.3% and a lifetime of 0.84s. At a brightness of 0.32 mcd m -2 that can be recognized by the naked eye, UOP can last for a total of 104 seconds. In view of these characteristics, ultra-long organic phosphorescent materials can be used for double data encryption and decryption. In addition, UOP nanoparticles dispersed in an aqueous solution were encapsulated by a polymer matrix, and their applications in biological imaging were investigated. This result will pave the way for metal-free organic phosphorescent materials and their applications. This work was published in the journal Advanced Materials on July 17, 2017 under the title "Visible-Light-Excited Ultralong Organic Phosphorescence by Manipulating Intermolecular Interactions" .

Literature link: Cai S, Shi H, Li J, et al. Visible-Light-Excited Ultralong Organic Phosphorescence by Manipulating Intermolecular Interactions [J]. Advanced Materials, 2017.

11. Thesis: Use of interdiffusion assisted composite two-dimensional MOF and Ti3C2Tx nanoflakes for electrocatalytic oxygen evolution reaction

ACS Nano published an article entitled "Interdiffusion Reaction-Assisted Hybridization of Two-Dimensional Metal-Organic Frameworks and Ti 3 C 2 T x Nanosheets for Electrocatalytic Oxygen Evolution" , which reported on Professor Li Shaozhou of Nanjing University of Posts and Telecommunications, and Huang of Nanjing University of Technology Professor Wei, Professor Huang Xiao (co-corresponding author), etc. , synthesized CoBDC in situ using an internal diffusion phase-assisted process and composited Ti3C2Tx nanosheets with it. The obtained composite material was applied to an electrochemical oxygen evolution reaction (OER). Under a 0.1M KOH electrolyte, the current density was 10 mA cm ^{− 2} and the Tafel slope at a potential of 1.64 V relative to a reversible hydrogen electrode. It is 48.2mV dec ^{- 1} . These properties exceed those of IrO 2 based catalysts and even more advanced transition metal based catalysts than previously reported. The CoBDC layer provides a porous structure and a large active surface area, and the excellent electrical conductivity and hydrophilicity of the Ti3C2Tx nanosheets make it possible to recombine Ti 3 C 2 T x − Fast transfer on CoBDC interface. At the same time, it is also convenient for the aqueous electrolyte to approach the surface of the catalytically active CoBDC. This nanosheet was further assembled into an air cathode to form a rechargeable zinc-air battery, and successfully led the LED to emit light.

Literature link: Interdiffusion Reaction-Assisted Hybridization of Two-Dimensional Metal-Organic Frameworks and Ti3C2Tx Nanosheets for Electrocatalytic Oxygen Evolution (ACS Nano, 2017, DOI: 10.1021 / acsnano.7b01409)

12. Thesis: A high-efficiency red LED-multi-quantum well perovskite material based on wet processing

Huang Wei and Wang Jianpu (co-corresponding author) from Nanjing University of Technology have successfully prepared pure red high-efficiency perovskite light-emitting devices using a simple and scalable method, which greatly promoted the application of organometallic halide perovskite light-emitting diodes. .

Researchers have introduced small inorganic cations Cs into perovskite films with multi-quantum well structures to prepare pure red high-efficiency perovskite light-emitting devices. The multi-quantum potential well structure not only facilitates the establishment of cubic CsPbBr 3 perovskite structure at low temperature, but also enables the Cs-based multi-quantum potential well to provide pure and stable red electroluminescence. This universal method for preparing a multi-quantum potential well perovskite material allows a high degree of freedom in controlling the crystallinity and morphology of the emission layer. The chloride contained in the device can further improve the crystallinity and optical performance of Cs-based perovskite multiple quantum potential wells, allowing the device to have a low switching voltage (2v), high external quantum efficiency (maximum 3.7%), and high brightness (Approximately 440 cd m ^{− 2 at} 4v ). These performance test results show that the Cs-based perovskite multi-quantum potential well LED is the best-performing red light perovskite LED. And the perovskite LED has a record stability, with a device life of more than 5 hours at a constant current density of 10 mA cm ^{− 2} . Researchers‘ related work shows that the multi-quantum potential well perovskite material has great potential for producing high-performance LEDs in the visible light range by mass production, which has great appeal for low-cost lighting and display fields.

Literature link : Efficient Red Perovskite Light-Emitting Diodes Based on Solution-Processed Multiple Quantum Wells(Advanced Materials, 2017, Doi / 10.1002 / adma.201606600 / full)

13. Thesis: Reduced dye / graphene composites can be used as organic cathode materials for high-energy lithium-ion batteries

Academician Huang Nanjing University and Professor Ting Yu, Nanyang Technological University (co-author), etc. to provide a method for preparing simple common vat dyes / graphite composite materials. The combination of sonication and hydrothermal method can be used to prepare a variety of reducing dye / graphite composite materials for high performance lithium ion battery cathode materials. For example, by reducing the π-π interaction between Green 8 and graphene sheets, researchers have obtained a stable composite structure, which can not only effectively inhibit the dissolution of active materials, but also ensure the rapid electrons during the electrochemical reaction. transmission. Therefore, the reduced green 8 / graphene (VG8 / G) composites exhibit good cycle stability and excellent high rate performance. This simple and versatile method can also be used to prepare reduced brown BR / graphene (VB BR / G) and reduced olive T / graphene (VO T / G) composites, both of which show excellent electrochemical performance and are highly The development of cathode materials for performance lithium-ion batteries provides a new direction.

Literature link : Toward High Energy Organic Cathodes for Li-Ion Batteries: A Case Study of Vat Dye / Graphene Composites (Adv. Funct. Mater., 2016, DOI: 10.1002 / adfm.201603603)

Published reviews:

1. Overview: Materials for large-area perovskite batteries

Academician Huang Nanjing University of Technology (Advanced Materials Research Institute), Professor Qin Tianshi teamin Advanced Functional Materials published in the journal entitled " Materials toward are at The Up-Scaling of Transition of Perovskite Solar Cells: Progress, Challenges and Strategies, " the review articles, the first One author is Associate Professor Wang Fangfang . In this review, the author first introduces the structure of perovskite photovoltaic devices and modules, and then discusses the research progress, current problems and solutions of large-area perovskite photovoltaic devices in detail from the perspective of various functional layer materials. , Including perovskite materials, hole transport materials, electron transport materials and electrode materials. In addition, several key factors affecting the stability of perovskite photovoltaic devices are analyzed. Finally, the development and strategy of large-area perovskite photovoltaic devices are summarized and prospected. In this article, the cooperation on the industrialization of large-area perovskite batteries has been suggested by Li Xinguo and Dr. Wu Xiao, the partners of BOE Technology Group . The authors of this paper are Fangfang Wang , Yezhou Cao, Cheng Chen, Qing Chen, Xiao Wu, Xinguo Li, Tianshi Qin , * and Wei Huang *

Article link: https://onlinelibrary.wiley.com/doi/full/10.1002/adfm.201803753

2. Overview: Preparation, properties and applications of two-dimensional luminescent materials

Academician Huang Wei from Northwestern Polytechnical University and Professor Huang Xiao and Professor Yonghua Chen (Communications) from Nanjing University of Technology jointly published a review article on Chem. Soc. Rev. applications. The first authors are Dr. Wang Zhiwei and Master Qiu Jingjing. The author summarizes two-dimensional luminescent materials into three major categories, namely two-dimensional inorganic luminescent materials, two-dimensional organic luminescent materials, and two-dimensional organic-inorganic hybrid luminescent materials, and reviews their preparation, properties, and applications. The author explains the preparation methods of each type of materials and discusses their structure and chemical properties. In particular, the relationship between structure and luminescence characteristics is discussed in detail. Finally, the author looks forward to the current potential applications of 2D luminescent materials as well as developing challenges and future opportunities.

Literature link : Two-dimensional light-emitting materials: preparation, properties and applications , (Chem. Soc. Rev., 2018, DOI: 10.1039 / c8cs00332g)

3. Overview: Application of lead-free organic-inorganic hybrid perovskites in photovoltaics

Academician Huang Wei of Nanjing University of Technology, Professor Chen Yonghua, and associate researcher Xia Yingdong (co-corresponding author) published a review entitled "Lead-free Organic-Inorganic Hybrid Perovskites for Photovoltaic Applications: Recent Advances and Perspectives" in Advanced Materials . In this review, the author reviews the latest research advances in lead-free perovskite from theoretical analysis and experimental explanation of crystal structure, film deposition, and device performance of lead-free perovskite. The importance of further understanding of the basic properties of lead-free hybrid perovskites was also discussed, especially those related to light.

Original link: Lead-free Organic–Inorganic Hybrid Perovskites for Photovoltaic Applications: Recent Advances and Perspectives ( Adv. Mater., 2017 , DOI: 10.1002 / adma.201605005 )

Source of information: material cattle