Advances in the design and application of highly efficient conjugated polymers and small molecules over the past years have enabled the rapid progress in the development of organic photovoltaic (OPV) technology as a promising alternative to conventional solar cells. Among the numerous OPV materials, benzodithiophene (BDT)-based polymers and small molecules have come to the fore in achieving outstanding power conversion efficiency (PCE) and breaking 10% efficiency barrier in the single junction OPV devices. Remarkably, the OPV device featured by BDT-based polymer has recently demonstrated an impressive PCE of 11.21%, indicating the great potential of this class of materials in commercial photovoltaic applications. In this review, we offered an overview of the organic photovoltaic materials based on BDT from the aspects of backbones, functional groups, alkyl chains, and device performance, trying to provide a guideline about the structure-performance relationship. We believe more exciting BDT-based photovol...

Molecular Design of Benzodithiophene-Based Organic Photovoltaic Materials.

Carbon dioxide (CO2) capture using solid sorbents has been recognized as a very promising technology that has attracted intense attention from both academic and industrial fields in the last decade. It is astonishing that around 2000 papers have been published from 2011 to 2014 alone, which is less than three years after our first review paper in this journal on solid CO2 sorbents was published. In this short period, much progress has been made and the major research focus has more or less changed. Therefore, we feel that it is necessary to give a timely update on solid CO2 capture materials, although we still have to keep some important literature results published in the past years so as to keep the good continuity. We believe this work will benefit researchers working in both academic and industrial areas. In this paper, we still organize the CO2 sorbents according to their working temperatures by classifying them as such: (1) low-temperature ( 400 °C). Since the sorption capacity, kinetics, recycling stability and cost are important parameters when evaluating a sorbent, these features will be carefully considered and discussed. In addition, due to the huge amounts of cost-effective CO2 sorbents demanded and the importance of waste resources, solid CO2 sorbents prepared from waste resources and their performance are reviewed. Finally, the techno-economic assessments of various CO2 sorbents and technologies in real applications are briefly discussed.

Recent advances in solid sorbents for CO2 capture and new development trends

Conjugated microporous polymers (CMPs) are a unique class of materials that combine extended π-conjugation with a permanently microporous skeleton. Since their discovery in 2007, CMPs have become established as an important subclass of porous materials. A wide range of synthetic building blocks and network-forming reactions offers an enormous variety of CMPs with different properties and structures. This has allowed CMPs to be developed for gas adsorption and separations, chemical adsorption and encapsulation, heterogeneous catalysis, photoredox catalysis, light emittance, sensing, energy storage, biological applications, and solar fuels production. Here we review the progress of CMP research since its beginnings and offer an outlook for where these materials might be headed in the future. We also compare the prospect for CMPs against the growing range of conjugated crystalline covalent organic frameworks (COFs).

Advances in Conjugated Microporous Polymers.

Morphology Control in Organic Solar Cells

The presence of an excessive concentration of CO2 in the atmosphere needs to be curbed with suitable measures including the reduction of CO2 emissions at stationary point sources such as power plants through carbon capture technologies and subsequent conversion of the captured CO2 into non-polluting clean fuels/chemicals using photo and/or electrocatalytic pathways. Porous materials have attracted much attention for carbon capture and in the recent past; they have witnessed significant advancements in their design and implementation for CO2 capture and conversion. In this context, the emerging trends in major porous adsorbents such as MOFs, zeolites, POPs, porous carbons, and mesoporous materials for CO2 capture and conversion are discussed. Their surface texture and chemistry, and the influence of various other features on their efficiency, selectivity, and recyclability for CO2 capture and conversion are explained and compared thoroughly. The scientific and technical advances on the material structure versus CO2 capture and conversion provide deep insights into designing effective porous materials. The review concludes with a summary, which compiles the key challenges in the field, current trends and critical challenges in the development of porous materials, and future research directions combined with possible solutions for realising the deployment of porous materials in CO2 capture and conversion.

Emerging trends in porous materials for CO2 capture and conversion

Two novel conjugated microporous networks, P-1 and P-2, with carbazole–spacer–carbazole topological model structures, were designed and prepared by FeCl3 oxidative coupling polymerization. Monomer m-1 (fluorenone spacer) was modified with a thiophene Grignard to form the fluorenyl tertiary alcohol monomer m-2, and this step can increase the polymerization branches from four to five and incorporate the polar –OH group into the building block. N2 adsorption isotherms show that, after modification, the Brunauer–Emmett–Teller (BET) surface area of P-2 (1222 m2 g−1) is two times that of P-1 (611 m2 g−1), and the total pore volume increases 1.63 times from 0.95 to 1.55 at P/P0 = 0.99. However, the domain pore size (centred at 1.19 nm) and the pore distribution of both networks are not changed. It demonstrates that the domain pore width may be determined by the size of the rigid carbazole–spacer–carbazole backbone, not the degree of crosslinking when the networks were prepared under same polymerization conditions in this system. Hydrogen physisorption isotherms of P-1 and P-2 show that the H2 storage can be up to 1.05 wt% and 1.66 wt% at 77 K and 1.1 bar, and the isosteric heat is 9.89 kJ mol−1 and 10.86 kJ mol−1, respectively. At 273 K and 1.1 bar, the CO2 uptake capacity of P-2 can be up to 14.5 wt% which is 1.63 times that of P-1 under the same conditions. The H2 and CO2 uptake capacities of P-2 are among the highest reported for conjugated microporous networks under similar conditions. The CO2/CH4 and CO2/N2 selectivity results indicate that P-1 exhibits a slightly higher separation ability than P-2. There is often a trade-off between absolute uptake and selectivity in other microporous organic polymers. Fine design and tailoring the topological structure of the monomer can change the adsorption isosteric enthalpy and optimize the gas uptake performance. The obtained networks with the carbazole–spacer–carbazole rigid backbone show promise for potential use in clean energy applications and the environmental field.

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Design and synthesis of novel carbazole–spacer–carbazole type conjugated microporous networks for gas storage and separation

A new two-dimensional (2D) organic small molecule, DCA3T(T-BDT), was designed and synthesized for solution-processed organic solar cells (OSCs). DCA3T(T-BDT) exhibited a deep HOMO energy level (−5.37 eV) and good thermal stability. The morphologies of the DCA3T(T-BDT):[6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) blends were investigated by atomic force microscopy and the crystallinity was explored by X-ray diffraction (XRD) and 2D grazing incidence wide-angle X-ray scattering (GIWAXS), respectively. The morphologies of the blends were strongly influenced by the blend ratio of DCA3T(T-BDT):PC61BM and annealing temperature. The effect of thermal annealing on the photovoltaic performance of DCA3T(T-BDT)-based small molecule organic solar cells (SMOSCs) was studied in detail. When DCA3T(T-BDT) was used as a donor with PC61BM as an acceptor, high efficiency SMOSCs with a power conversion efficiency of 7.93%, a high Voc of 0.95 V, Jsc of 11.86 mA cm−2 and FF of 0.70 were obtained by a thermal annealing process at only 60 °C, which offers obvious advantages for large scale production compared with solvent additive or interfacial modification treatment.

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Shanlin Qiao

Papers

Design and synthesis of novel carbazole–spacer–carbazole type conjugated microporous networks for gas storage and separation

High efficiency solution-processed two-dimensional small molecule organic solar cells obtained via low-temperature thermal annealing

High‐Efficiency Polymer Solar Cells Over 13.9% With a High VOC Beyond 1.0 V by Synergistic Effect of Fluorine and Sulfur

Ternary Polymer Solar Cells with High Efficiency of 14.24% by Integrating Two Well-Complementary Nonfullerene Acceptors

Prevailing conjugated porous polymers for electrochemical energy storage and conversion: Lithium-ion batteries, supercapacitors and water-splitting