Materials Chemistry Frontiers Blog

As a joint venture between the chemistry communities of China and the UK, Materials Chemistry Frontiers strives to report the best research from China and rest of the world to international audiences.

Board members of the journal regularly select and feature their favorite MCF articles that represent research the members see as possessing exceptional novelty and a potential impact to the development of the field.

This month, Editorial Board member Zhen Li picked his choice articles from those published in Materials Chemistry Frontiers during June and July 2017.

All these articles are now FREE to read.

@MaterChem on Twitter to tell us how you think about them.

Design and effective synthesis methods for high-performance polymer semiconductors in organic field-effect transistors

Longxian Shi, Yunlong Guo, Wenping Hu and Yunqi Liu  
Mater. Chem. Front., 2017, Advance Article
DOI: 10.1039/C7QM00169J, Review Article
First published on 07 Jul 2017

Editor’s comments:

Organic field effect transistors (OFETs), important components of organic electronics, have witnessed lots of breakthrough, partially due to their potential applications in radio frequency identification (RFID) tags, flexible displays, electronic papers, sensor and so forth. Thanks to the advantages of flexibility, light weight, transparency, solution-processability and modifiability, polymer semiconductors are one of the favorite choices for OFETs. In this Review Article, Yunlong Guo, Wenping Hu, and Yunqi Liu and coworkers from Institute of Chemistry, Chinese Academy of Sciences (China) and Tianjing University (China) summarized the progress of the third-generation donor-acceptor (D-A) polymers for OFETs with high performance, especially emphasizing on building block selection, backbone halogenation, side chain engineering and random copolymerization. They pointed out that once the chemical approaches mentioned above are combined with rational device architectures, more high-performance polymer based OFETs are expected.

Molecular conformation and packing: their critical roles in the emission performance of mechanochromic fluorescence materials

Can Wang and Zhen Li
Mater. Chem. Front., 2017, Advance Article
DOI: 10.1039/C7QM00201G, Review Article
First published on 07 Jun 2017

Editor’s comments:

The development of mechanochromic fluorescence (MCF) materials has attracted much attention due to their great potential in data storage, anti-counterfeiting, pressure sensors and display. However, the significantly variety in the origin of this stimuli-responsive systems makes it challenging to establish a general and specific design strategies to create new high-contrast MCF materials. In this Review Article, Zhen Li and co-worker from Wuhan University (China) summarized the mechanisms of different MCF cases from the viewpoint of molecular packing status, intermolecular interactions, and intramolecular conformation in polymorphism MCF systems. The critical roles of molecular packing and conformation in the force-to-luminescence process are discussed. The general thoughts of structure–packing–performance generated from the MCF materials might promote the further optimization of organic material performance in aggregated state.

High rate Li-ion storage properties of MOF-carbonized derivatives coated on MnO nanowires

Zhen-Dong Huang, Zhen Gong, Qi Kang, Yanwu Fang, Xu-Sheng Yang, Ruiqing Liu, Xiujing Lin, Xiaomiao Feng, Yanwen Ma and Dan Wang
Mater. Chem. Front., 2017, 1, 1975-1981
DOI: 10.1039/C7QM00178A, Research Article
First published on 02 Jun 2017

Editor’s comments:

The supply of power is one of the most important issues in modern life. Nowadays, lithium-ion batteries (LIBs) are still the leading power sources for electrical vehicles and still predominate in the battery market for portable electronic devices and green energy distribution. To break the limit of traditional LIBs with graphite as the anode material, many efforts have been attempted. In this Article, Yanwen Ma, Dan Wang and coworkers from Nanjing University of Posts & Telecommunications (China) and Institute of Process Engineering Chinese Academy of Sciences (China) utilized zeolitic imidazolate framework (ZIF) types of MOF strung by MnO₂ NWs as precursors, to prepare C/Co-coated MnO nanowires (C/Co-MnO NWs), which could deliver 848.4 and 718 mA h g^-1 at 500 and 5000 mA g^-1 after 40 charge/discharge cycles, respectively, superior to other reported MOF-derived nanostructured materials.

In situ polymerized hyperbranched polymer reinforced poly(acrylic acid) hydrogels

Nazila Dehbari, Javad Tavakoli, Simranjeet Singh Khatrao and Youhong Tang
Mater. Chem. Front., 2017, 1, 1995-2004
DOI: 10.1039/C7QM00028F, Research Article
First published on 06 Jun 2017

Editor’s comments:

Hydrogels, a special kind of three-dimensional cross-linked, water-swollen and hydrophilic polymers, have been extensively investigated for use in various applications as enviro-sensitive materials. Among various types of hydrogels, polyacrylate polymers such as polyacrylic acid (PAA) have the most versatile structure to enhance their practical utility in everyday life applications such as filtration, water remediation, diapers and hygiene products, cosmetics, wound dressings, medical waste solidification and metal ion removal. However, regardless of many advantages, the poor mechanical property of PAA hydrogels is considered as a marked weakness, and limited their specific applications. In this Article, Youhong Tang and coworkers from Flinders University (Australia) intelligently introduced a hyperbranched polymer into PAA, through in situ polymerization, to toughen PAA hydrogels with 130% improvement in the ultimate tensile strength, without sacrificing the swelling ratio.

Highly efficient thermally activated delayed fluorescence materials with reduced efficiency roll-off and low on-set voltages

Haobin Zhao, Zhiheng Wang, Xinyi Cai, Kunkun Liu, Zuozheng He, Xin Liu, Yong Cao and Shi-Jian Su
Mater. Chem. Front., 2017, 1, 2039-2046
DOI: 10.1039/C7QM00195A, Research Article
First published on 13 Jun 2017

Editor’s comments:

Prompted by both scientific and commercial interests, organic materials with high performance are badly needed to be explored for organic light-emitting diodes (OLEDs). Specially, metal-free thermally activated delayed fluorescence (TADF) materials can achieve 100% use of excitons through reverse intersystem crossing (RISC) because of their low energy gap (DEST) between the lowest singlet excited state (S1) and the triplet excited state (T1). In this Article, Shijian Su, Yong Cao and coworkers from South China University of Technology (China) combined carbazole and two additional carbazole or diphenylamine moieties together with a benzophenone unit, to design two donor–acceptor (D–A) type TADF luminogens of CCDC and CCDD. A maximal EQE of 15.9%, the highest ever value among the reported benzophenone-based blue emitters, was achieved in the blue-emitting devices with CCDC as the emitter. And the green emitting CCDD-based devices demonstrated the maximal EQEs exceed 22% and the on-set voltages of as low as 2.6 V.

Morphology control enables thickness-insensitive efficient nonfullerene polymer solar cells

Xiaoyu Liu, Long Ye, Wenchao Zhao, Shaoqing Zhang, Sunsun Li, Gregory M. Su, Cheng Wang, Harald Ade and Jianhui Hou
Mater. Chem. Front., 2017, 1, 2057-2064
DOI: 10.1039/C7QM00182G, Research Article
First published on 22 Jun 2017

Editor’s comments:

Solution-processed bulk heterojunction (BHJ) polymeric solar cells (PSCs) have attracted extensive attention in the past two decades due to their low cost, light weight, and potential for roll-to-roll production on flexible substrates. Instead of using fullerene acceptors, due to the efforts of scientists, especially the contributions from Xiaowei Zhan’s group (Peking University, China), some PSCs comprising conjugated polymers and non-fullerene acceptors have demonstrated high power-conversion efficiencies (PCE > 12%). So far, one of the major factors hindering industrial production of nonfullerene PSCs is the high sensitivity of the power conversion efficiency (PCE) to thickness variations, which can significantly affect the manufacturing yields and production costs of roll-to-roll processing. When the thickness of the active layer is over 100 nm, PCEs show a significant loss. In this Article, Long Ye, Shaoqing Zhang, Harald Ade and Jianhui Hou from University of Science and Technology Beijing (China), Institute of Chemistry, Chinese Academy of Sciences (China), and North Carolina State University (USA) reported that simply via thermal annealing, highly efficient thickness-insensitive non-fullerene PSCs could fabricated. For example, PBDB-T/IT-M-based nonfullerene PSCs can afford an impressive PCE of up to 9.4% at an active layer thickness of 250 nm, and a high efficiency close to 9%@400 nm, contributing much for the possible commercial roll-to-roll printing technology.

Previous articles recommended by MCF board members are also open for all to access. Read the full collection now!

As a joint venture between the chemistry communities of China and the UK, Materials Chemistry Frontiers strives to report the best research from China and rest of the world to international audiences.

Board members of the journal regularly select and feature their favorite MCF articles that represent research the members see as possessing exceptional novelty and a potential impact to the development of the field.

This month, Associate Editor Shu Seki picked his choice articles from those published in Materials Chemistry Frontiers during April and May 2017.

All these articles are now FREE to read.

@MaterChem on Twitter to tell us how you think about them.

Magnetic-field effects in ambipolar transistors based on a bipolar molecular glass

Thomas Reichert, Georg Hagelstein and Tobat P. I. Saragi
Mater. Chem. Front., 2017, Advance Article
DOI: 10.1039/C7QM00104E, Research Article
First published on 10 Apr 2017

Editor’s comments:

Huge variety of organic semiconductive molecular materials has been reported day-by-day in these years, and the devices based on the materials are mainly of interests with efficient charge transporting properties. The nature of charge carriers themselves, however, has been seldom clarified in many cases. The magnetoresistance in a bipolar semiconductive molecular glass, discussed in the present paper by Reichert, Hagelstein, and Saragi, provides a clear picture of the charge carriers of which spins are in a variety of coupling interactions. The magnetic responses of the devices offer the multi-functional device systems responding external magnetic field, as the authors claim, and will contribute to figure out fundamentally the characters of charge carriers themselves.

Direct amination of the antiaromatic NiII norcorrole

Takuya Yoshida and Hiroshi Shinokubo
Mater. Chem. Front., 2017, Advance Article
DOI: 10.1039/C7QM00176B, Research Article
First published online on 10 May 2017

Editor’s comments:

Likely to the aromatic porphyrin derivatives studied widely in everywhere, anti-aromatic norcorroles will be a fundamental and important class of ‘porphyrinoids’ in their condensed phases via p-electron interaction through spaces.  The direct amination reactions discovered and demonstrated in the present paper by Yoshida and Shinokubo are very simple approach to functionalize the molecular motifs with region-selectivity via C-H activation. This might be the easiest way to introduce electron donating amino groups into porphynoids, leading to the fine tuning of energy levels with pretty high chemical yields.

The ‘folklore’ and reality of reticular chemistry

Kyle E. Cordova and Omar M. Yaghi
Mater. Chem. Front., 2017, 1, 1304-1309
DOI: 10.1039/C7QM00144D, Chemistry Frontiers
First published on 05 May 2017

Editor’s comments:

Scientists working on “reticular chemistry” linking molecular building blocks by strong bonds to make porous frameworks, by the authors, will empathize the three folklores in this frontier article.  However, the comments in this article, especially in conclusions, will be fruitful for most of all chemists working on ‘The Atom and the Molecule’ to think and design their own future molecular systems as the frontier of materials.

Previous articles recommended by MCF board members are also open for all to access. Read the full collection now!

As a joint venture between the chemistry communities of China and the UK, Materials Chemistry Frontiers strives to report the best research from China and rest of the world to international audiences.

Board members of the journal regularly select and feature their favourite MCF articles that represent research the members see as possessing exceptional novelty and a potential impact to the development of the field.

This month, Associate Editor Dan Wang picked his choice articles from those published in Materials Chemistry Frontiers during February and March 2017. This selection of articles focuses on the preparation of hybrid or nanomaterials and their promising applications in energy conversion and storage.

All these articles are now FREE to read.

@MaterChem on Twitter to tell us how you think about them.

Research progress regarding Si-based anode materials towards practical application in high energy density Li-ion batteries

Jin-Yi Li, Quan Xu, Ge Li, Ya-Xia Yin, Li-Jun Wan* and Yu-Guo Guo*  
DOI: 10.1039/C6QM00302H, Review Article
First published online on 20 Feb 2017

Editor’s Comments:

Si-based anode materials provide a promising way to improve the energy density of lithium-ion batteries (LIBs) due to its environmentally friendly character, natural abundance, high theoretical capacity and attractive operating voltage. However, huge volume variation during lithiation/delithiation and low electric conductivity of Si make it challenging for practical applications of Si-based materials. Yu-Guo Guo and coworkers at Institute of Chemistry, Chinese Academy of Sciences analyzed the mechanisms of Li-Si alloying and cell failure of Si-based anodes and summarized research progress of Si-based anode materials. To obtain high reversible capacity and excellent cycling stability, nano/micro-structured Si/C and SiO_x/C composite anodes with 3D conductive networks and stable interfaces are discussed. The researchers proposed the key aspects of Si-based materials and prospective strategies for promoting the practical applications of Si-based anodes in high energy density Li-ion batteries.

High-quality organohalide lead perovskite films fabricated by layer-by-layer alternating vacuum deposition for high efficiency photovoltaics

Mohammad Mahdi Tavakoli, Abdolreza Simchi, Xiaoliang Mo* and Zhiyong Fan*
DOI: 10.1039/C6QM00379F, Research Article
First published online on 06 Feb 2017

Editor’s Comments:

A new procedure to fabricate stoichiometric, uniform, and highly crystalline lead perovskite thin films. In this work, Fan et al. at The Hong Kong University of Science and Technology developed a layer-by-layer alternating (LBLA) vacuum deposition method to obtain methylammonium lead iodide thin films with much improved morphology, thickness uniformity and composition stoichiometry, as compared with previously reported two-step thin film deposition method. Characterizations show that LBLA films have higher crystallinity and longer carrier life-time. The better film quality leads to 20% improved power conversion efficiency in thin film perovskite solar devices, primarily owing to a higher fill factor and current density.

Ternary silver chlorobromide nanocrystals: intrinsic influence of size and morphology on photocatalytic activity

Sasitha C. Abeyweera and Yugang Sun* 
DOI: 10.1039/C7QM00046D, Research Article
First published online on 09 Mar 2017

Editor’s Comments:

Stirring rate plays a significant role in determining the mass diffusion and thus nucleation and growth kinetics of forming colloidal nanocrystals in particular in high-viscosity solutions even though its importance is usually overlooked.  By controlling the rate of solution stirring, Abeyweera and Sun from Temple University demonstrated the successful synthesis of various silver chlorobromide (AgCl_xBr_1-x) nanoparticles with well-controlled sizes and morphologies through precipitation reaction of silver ions and halide ions in ethylene glycol.  The as-synthesized AgCl_xBr_1‒x nanoparticles provide a unique platform to accurately study the dependence of their photocatalytic activity on particle size (which determines charge separation efficiency) and morphology (which determines the type of catalytic surfaces).

Fabrication of core–shell, yolk–shell and hollow Fe₃O₄@carbon microboxes for high-performance lithium-ion batteries

Hao Tian, Hao Liu*, Tianyu Yang, Jean-Pierre Veder, Guoxiu Wang, Ming Hu, Shaobin Wang, Mietek Jaroniec* and Jian Liu*
DOI: 10.1039/C7QM00059F, Research Article
First published on 06 Mar 2017

Editor’s comments:

This work presents a facile synthetic procedure of Fe₃O₄@carbon microboxes with core-shell, yolk-shell and hollow structures via one-step Stöber coating synthesis. Dr Jian Liu and co-workers working primarily at Curtin University, Australia, with connections to Shanghai University, China, and Kent State University, USA have synthesized a series of Fe₃O₄@carbon microboxes. When applied as electrodes in a lithium ion battery, the core–shell structured Fe₃O₄@carbon microboxes show an excellent performance with a high reversible capacity of 857 mA h g⁻¹ that could be retained after 100 cycles at a current density of 0.1 A g⁻¹. Their results revealed that a great performance of the Fe₃O₄@carbon microboxes proves the importance of rational design and fabrication of core–shell particles with tuneable structures, multi-chemical composition and improved functionalities.

*This article is also featured as the front cover story for Mater. Chem. Front., Vol 1, Iss 5.

High open-circuit voltage ternary organic solar cells based on ICBA as acceptor and absorption-complementary donors

Jin Fang, Dan Deng, Jianqi Zhang, Yajie Zhang, Kun Lu and Zhixiang Wei*
DOI: 10.1039/C6QM00308G, Research Article
Published as Advance Articles on 06 Feb 2017

Editor’s comments:

A potential strategy to improve the performance of organic solar cells (OSCs), ternary OSCs based on indene-C₆₀ bisadduct (ICBA) electron acceptor and absorption-complementary electron donors, was reported by Wei and co-workers from National Center for Nanoscience and Technology, China. A high open-circuit voltage of 0.98 V is obtained. The performance of ternary OSCs is improved by 10% attributed to the optimized morphology with better crystalline electron donors and acceptor after blending solution processing small molecules. The reported studies reveal a new method for enhancing the performance of ICBA and non-fullerene based OSCs.

Previous articles recommended by MCF board members are also open for all to access. Read the full collection now!