Chunyue Pan

Copolymers from benzodithiophene and benzotriazole: synthesis and photovoltaic applications

Two new alternating low bandgap copolymers from benzodithiophene and benzotriazole units, namely poly{4,8-bis(2-ethylhexyloxy)benzo[1,2-b; 3,4-b]dithiophene-2,6-diyl-alt-2-octyl-4,7-di(thiophen-2-yl)-2H-benzo[d][1,2,3]triazole-5′,5′′-diyl} (PBDTDTBTz) and poly{4,8-bis(2-ethylhexyloxy)benzo[1,2-b;3,4-b]dithiophene-2,6-diyl-alt-2-dodecylbenzotriazole-4,7-diyl} (PBDTBTz), were designed and synthesized by a typical Stille coupling polymerization method. The copolymers were characterized by thermogravimetric analysis, UV-vis absorption and cyclic voltammetry. PBDTDTBTz and PBDTBTz possess moderate molecular weights and excellent thermal properties with a 5% weight loss temperatures (Td) around 300 °C. They exhibited good optical absorption, with peaks at 527 nm and 562 nm in the film state, respectively. Photovoltaic properties of the copolymers blended with [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) or [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as electron acceptors, were investigated. The photovoltaic device with the PBDTDTBTz/PC71BM shows a power conversion efficiency of 1.7% with a short circuit current density of 4.5 mA cm−2 and a good fill factor of 0.62, while PBDTBTz demonstrated a moderate power conversion efficiency of up to 1.4%, under the illumination of AM 1.5, 100 mW cm−2 with a device structure of ITO/PEDOT: PSS/polymer: PC71BM (1 : 4)/Ca/Al. All the above information highlighted that this kind of the copolymers is promising for the application of polymer solar cells.

Low bandgap isoindigo-based copolymers : design, synthesis and photovoltaic applications

Three new low bandgap isoindigo-based conjugated polymers were synthesized, namely poly {(N-octyl)-carbazole-2,7-diyl-alt-[N,N′-(2-ethylhexyl)-isoindigo]-6′,6′′-diyl} (PCzID), poly{(9, 9-dioctylfluorene)-2,7-diyl-alt-[N,N′-(2-ethylhexyl)-isoindigo]-6′,6-diyl} (PFID), and poly{4, 8-bis(2-ethylhexoxy)-benzo[1, 2-b,3,4-b]-dithiophene-2,6-diyl-alt-[N,N′-(2-ethylhexyl)-isoindigo]-6′,6′′-diyl} (PBDTID), by Stille or Suzuki coupling polymerization reaction. All of the polymers were soluble in common organic solvents, such as chloroform, tetrahydrofuran, and chlorobenzene with good film forming properties. The polymer films exhibit broad absorption bands in the wavelength region from 300 nm to 810 nm. Especially, PBDTID possesses the smallest bandgap of 1.54 eV calculated from its absorption cut-off at 806 nm. Preliminary photovoltaic cells based on the device structure of ITO/PEDOT:PSS/PBDTID:PC60BM (1:1 w/w)/Ca/Al showed an open-circuit voltage of 0.56 V, a power conversion efficiency of 0.9% and a short circuit current of 3.81 mA cm−2.

Performance improvement of polymer solar cells by using a solvent-treated poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) buffer layer

Photovoltaic performance of the polymer solar cell (PSC) based on poly(3-hexylthiophene) (P3HT) as donor and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) as acceptor was improved by using the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) modification layer treated by ethanol or 2-propanol. Power conversion efficiency (PCE) of the PSC based on P3HT:PCBM (1:1, w/w) with the 2-propanol-treated PEDOT:PSS modification layer reached 4.74%, in comparison with a PCE of 3.39% for the PSC with the PEDOT:PSS layer without the organic solvent treatment. The enhanced performance of the PSCs is attributed to higher conductivity and optimized surface morphology of the PEDOT:PSS layers treated by the organic solvent.

Liquid acid-catalysed fabrication of nanoporous 1,3,5-triazine frameworks with efficient and selective CO2 uptake

New classes of nanoporous organic polymers based on 1,3,5-triazine units (NOP-1–6) were synthesized via a straightforward, methane-sulfonic acid-catalysed, cost-effective Friedel–Crafts reaction of 2,4,6-trichloro-1,3,5-triazine and tetrahedral building blocks. Among them, NOP-3 with a Brunauer–Emmet–Teller (BET) specific surface area up to 894 m2 g−1 and the total volume exceeding 0.41 m3 g−1 exhibits good hydrogen adsorption capacity (up to 1.14 wt% at 77 K/1.0 bar) and high carbon dioxide uptake (up to 11.03 wt% at 273 K/1.0 bar). Furthermore, it presents an effective selectivity for CO2 adsorption (NOP-6, CO2/N2 selectivity 38.7 at 273 K/1.0 bar), demonstrating potential applications in gas adsorption and separation.

A rational construction of microporous imide-bridged covalent–organic polytriazines for high-enthalpy small gas absorption

A series of microporous imide functionalized 1,3,5-triazine frameworks (named TPIs@IC) were designed by an easy-construction technology other than the known imidization method for the construction of porous triazine-based polyimide networks (TPIs) with the same chemical compositions. In contrast to TPIs, TPIs@IC exhibit much higher Brunauer–Emmett–Teller (BET) surface areas (up to 1053 m2 g−1) and carbon dioxide uptake (up to 3.2 mmol g−1/14.2 wt% at 273 K/1 bar). The presence of abundant ultramicropores at 5.4–6.8 A, mainly ascribed to a high-level cyano cross-linking, allows the high heat absorption and high selective capture of CO2. The Qst (CO2 esoteric enthalpies) from their CO2 adsorption isotherms at 273 and 298 K are calculated to be in the range 46.1–49.3 kJ mol−1 at low CO2 loading, and the ideal CO2/N2 separation factors are up to 151, exceeding those of the most reported porous organic polymers to date. High storage capacities of TPIs@IC for other small gases like CH4 (5.01 wt% at 298 K/22 bar) and H2 (1.47 wt% at 77 K/1 bar) were also observed, making them promising adsorbents for gas adsorption and separation.

New alkoxylphenyl substituted benzo[1,2-b:4,5-b′] dithiophene-based polymers: synthesis and application in solar cells

Two new alkoxylphenyl substituted benzo[1,2-b:4,5-b′]dithiophene (BDTPO)-based polymers (PBDTPO-DTBO and PBDTPO-DTBT) were synthesized. Their structures were verified by NMR spectroscopy, the molecular weights were determined by gel permeation chromatography (GPC), and the thermal properties were investigated by thermogravimetric analysis (TGA). UV-Vis absorption spectra of the polymers show broad and strong absorption bands from 300–750 nm both in CHCl3 solutions and films. The resulting copolymers exhibit relatively deep HOMO energy levels (−5.56 and −5.46 eV) and surprisingly high hole mobilities (2.2 × 10−1 and 3.3 × 10−2 cm2 V−1 s−1) for PBDTPO-DTBO and PBDTPO-DTBT, respectively. Preliminary photovoltaic properties of the copolymers blended with [6,6]-phenyl-C71 (or 61)-butyric acid methyl ester (PCBM) as an electron acceptor were investigated. The polymer solar cell (PSC) based on the single layer device structure of ITO/PEDOT:PSS/PBDTPO-DTBO:PC71BM (1 : 1.5, w/w)/Ca/Al demonstrates a high power conversion efficiency of 6.2% under the illumination of AM 1.5G, 100 mW cm−2.

Tunable porosity of nanoporous organic polymers with hierarchical pores for enhanced CO2 capture

A series of cost-effective nanoporous organic polymers (NOP-50–NOP-52) with hierarchical pores for efficient CO2 capture were successfully synthesized via one-step Friedel–Crafts alkylation promoted by anhydrous FeCl3. Two chloromethyl monomers, i.e. dichloroxylene (DCX) and 4,4′-bis(chloromethyl)-1,1′-biphenyl (BCMBP) were utilized as crosslinkers to tailor the pore sizes. The porosity of the resultant polymers can be well-tuned by varying the length of crosslinkers and type of building blocks. More specifically, shorter linkers provide the polymers with greater microporosity, whereas longer linkers prove to block the microporosity created by the high-degree crosslinking of organic network. Introducing a series of highly rigid, nitrogen-containing, or metal-decorated building blocks features the obtained amorphous networks abundant microporosity and mesoporosity, and large Brunauer–Emmett–Teller (BET) surface areas up to 1650 m2 g−1 as measured by N2 adsorption at 77 K. Notably, such networks possess hierarchical pores with wide pore size distributions ranging from 0.55 to 4.3 nm. NOP-50A derived from DCX and carbazole exhibits competitive CO2 uptake up to 18.8 wt% at 273 K and 1 bar, surpassing most known HCPs. Remarkable selectivity ratios for CO2 adsorption over N2 (39–72) at 273 K and high CO2 isoteric heats of adsorption (34.2–46.7 kJ mol−1) were obtained. The high CO2/N2 selectivity and CO2 isosteric heat values could be ascribed to the good binding affinity of abundantly available electron-rich basic heteroatom or metal sites of the networks towards CO2. These results are significant for the construction of NOPs with hierarchical pores by introducing optimum building block and suitable length linkers for enhanced CO2 capture.

Facile Carbonization of Microporous Organic Polymers into Hierarchically Porous Carbons Targeted for Effective CO2 Uptake at Low Pressures

The advent of microporous organic polymers (MOPs) has delivered great potential in gas storage and separation (CCS). However, the presence of only micropores in these polymers often imposes diffusion limitations, which has resulted in the low utilization of MOPs in CCS. Herein, facile chemical activation of the single microporous organic polymers (MOPs) resulted in a series of hierarchically porous carbons with hierarchically meso-microporous structures and high CO2 uptake capacities at low pressures. The MOPs precursors (termed as MOP-7-10) with a simple narrow micropore structure obtained in this work possess moderate apparent BET surface areas ranging from 479 to 819 m(2) g(-1). By comparing different activating agents for the carbonization of these MOPs matrials, we found the optimized carbon matrials MOPs-C activated by KOH show unique hierarchically porous structures with a significant expansion of dominant pore size from micropores to mesopores, whereas their microporosity is also significantly improved, which was evidenced by a significant increase in the micropore volume (from 0.27 to 0.68 cm(3) g(-1)). This maybe related to the collapse and the structural rearrangement of the polymer farmeworks resulted from the activation of the activating agent KOH at high temperature. The as-made hierarchically porous carbons MOPs-C show an obvious increase in the BET surface area (from 819 to 1824 m(2) g(-1)). And the unique hierarchically porous structures of MOPs-C significantly contributed to the enhancement of the CO2 capture capacities, which are up to 214 mg g(-1) (at 273 K and 1 bar) and 52 mg g(-1) (at 273 K and 0.15 bar), superior to those of the most known MOPs and porous carbons. The high physicochemical stabilities and appropriate isosteric adsorption heats as well as high CO2/N2 ideal selectivities endow these hierarchically porous carbon materials great potential in gas sorption and separation.

A Luminescent Hypercrosslinked Conjugated Microporous Polymer for Efficient Removal and Detection of Mercury Ions

A hypercrosslinked conjugated microporous polymer (HCMP-1) with a robustly efficient absorption and highly specific sensitivity to mercury ions (Hg(2+)) is synthesized in a one-step Friedel-Crafts alkylation of cost-effective 2,4,6-trichloro-1,3,5-triazine and dibenzofuran in 1,2-dichloroethane. HCMP-1 has a moderate Brunauer-Emmett-Teller specific surface (432 m(2) g(-1)), but it displays a high adsorption affinity (604 mg g(-1)) and excellent trace efficiency for Hg(2+). The π-π* electronic transition among the aromatic heterocyclic rings endows HCMP-1 a strong fluorescent property and the fluorescence is obviously weakened after Hg(2+) uptake, which makes the hypercrosslinked conjugated microporous polymer a promising fluorescent probe for Hg(2+) detection, owning a super-high sensitivity (detection limit 5 × 10(-8) mol L(-1)).

Metal Microporous Aromatic Polymers with Improved Performance for Small Gas Storage

A novel metal-doping strategy was developed for the construction of iron-decorated microporous aromatic polymers with high small-gas-uptake capacities. Cost-effective ferrocene-functionalized microporous aromatic polymers (FMAPs) were constructed by a one-step Friedel-Crafts reaction of ferrocene and s-triazine monomers. The introduction of ferrocene endows the microporous polymers with a regular and homogenous dispersion of iron, which avoids the slow reunion that is usually encountered in previously reported metal-doping procedures, permitting a strong interaction between the porous solid and guest gases. Compared to ferrocene-free analogues, FMAP-1, which has a moderate BET surface area, shows good gas-adsorption capabilities for H2 (1.75 wt % at 77 K/1.0 bar), CH4 (5.5 wt % at 298 K/25.0 bar), and CO2 (16.9 wt % at 273 K/1.0 bar), as well as a remarkably high ideal adsorbed solution theory CO2 /N2 selectivity (107 v/v at 273 K/(0-1.0) bar), and high isosteric heats of adsorption of H2 (16.9 kJ mol(-1) ) and CO2 (41.6 kJ mol(-1) ).