Mingjun Li

Quasi-solid-state dye-sensitized solar cell from polyaniline integrated poly(hexamethylene diisocyanate tripolymer/polyethylene glycol) gel electrolyte

A microporous hydrophobic polyaniline (PANi) integrated poly(hexamethylene diisocyanate tripolymer/polyethylene glycol) [poly(HDT/PEG)] gel electrolyte was successfully synthesized via a two-step aqueous solution polymerization process. An ionic conductivity of 12.11 mS cm−1 at room temperature was obtained for the PANi integrated poly(HDT/PEG) gel electrolyte, which was well characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, electrochemical impedance spectroscopy, and cyclic voltammetry. Morphological observations showed that the resultant gel electrolyte exhibits microporous structure, providing space for holding I−/I3− liquid electrolyte. The integration of PANi with poly(HDT/PEG) causes a lower charge-transfer resistance and higher electrocatalytic activity for the I−/I3− redox reaction. A dye-sensitized solar cell with a photo-to-electric conversion efficiency of 6.81% was obtained by sandwiching PANi integrated poly(HDT/PEG) gel electrolyte between a TiO2 anode and a Pt counter electrode, under illumination with simulated solar light of 100 mW cm−2 (AM 1.5).

Small bandgap naphthalene diimide copolymers for efficient inorganic–organic hybrid solar cells

Two low band-gap naphthalene diimide (NDI)-based conjugated polymers have been designed and grafted with benzo[1,2-b:4,5-b′]dithiophene (BDT) or dithieno [3,2-b:2′,3′-d]pyrrole (DTP) by a Stille cross-coupling reaction. Inorganic–organic hybrid solar cells (HSCs) based on the copolymers deliver high performances by suitable molecular design and careful selection of chemical structures with different electronic nature. The well designed copolymers exhibit broader solar light absorption, which is attributed to their smaller band gaps. Density functional theory calculations and cyclic voltammetry characteristics reveal that the copolymers have small band gaps and deep HOMO and LUMO energy levels. Moreover, after introducing the copolymers, the energy level formation of the bulk-heterojunction become more matched, thus giving rise to excellent photovoltaic performances as HSCs. The results showed that an NDI-based copolymer with DTP donor segments exhibits a higher power conversion efficiency of 2.36%. This work highlights the development of bipolar host materials with a focus on molecular design strategies, which benefits the light harvest and enhances the efficiency by well aligned energy level formation.

Novel benzo(1,2-b:4,5-b’)dithiophene-based donor–acceptor conjugated polymes for polymer solar cells

Two new donor–acceptor (D-A) alternative copolymers, poly{4-(5-(4,8-bis(dodecyloxy)-6-methylbenzo[1,2-b:4,5-b’]-dithiophen-2-yl) -4–dodecylthiophen-2-yl)-2-dodecyl-7-(4-dodecyl-5-methylthiophen-2-yl)-2H-benzo[d] [1–3] triazole} (P1) and poly{4-(5-(4,8-bis(dodecyloxy)-6-methylbenzo -[1,2-b:4,5-b’]dithiophen-2-yl)-4-dodecylthiophen-2-yl)-2-dodecyl-9-(4-dodecyl-5methylthiophen-2-yl)-6,7-dimethyl-2H- [1–3] triazolo[4,5-g]quinoxaline} (P2), were designed and synthesized. Also, the effects of the structural variation on their properties, especially their UV and electrochemical behaviors, were studied. The polymers were verified by NMR and characterized by TGA, UV–vis absorption and electrochemical cyclic voltammetry. It was found that P1 exhibits stronger π-π stacking and aggregation in solid film related to in solution state than those of P2. All the polymers show narrow band gaps, with the electro-chemical band gaps (EgEC) 1.45xa0eV for P1 and 1.61xa0eV for P2. Interestingly, the polymer P2 exhibits power conversion efficiency (PCE) of 2.2xa0%, while the copolymer P1 shows an improvement PCE of 2.9xa0%. It indicates that mildly tailoring the acceptor segments of the D-A copolymer is a facile and promising approach for active layer engineering to developing high performance polymer solar cells.

Simple synthesis regarding novel bianchored metal free organic dyes based on indole for dye sensitized solar cells

Two indole-based bianchored metal free organic dyes (D1 and D2) organic dyes were designed and conveniently prepared for dye sensitized solar cells application. Indole moiety was utlised as the electron donor, conjugated system thiophene unit as the π-bridge, rodanine-3-acetic acid and cyanoacrylic acid groups as the electron acceptor. The maximum conversion rate of photovoltaic devices focused on D2, which achieved a conversion of 5.13xa0% under AM 1.5 illumination.

Hyperbranched small-molecule electrolyte as cathode interfacial layers for improving the efficiency of organic photovoltaics

Small-molecule electrolytes (SMEs) have attracted increasing interests owing to their intrinsic advantages, such as high repeatability, easy purification and well-defined structures. Interfacial engineering plays crucial roles in enhancing the power conversion efficiency (PCE) of polymer solar cells (PSCs). Through a green route one-step reaction with nonhalogen solvent, we reported the design and synthesis of one novel hyperbranched SME PNSO3Na as cathode interfacial layer (CIL). Owing to containing seven moles butyl sulfonate sodium, hyperbranched SMEs PNSO3Na CIL can form interfacial dipoles, tune the interfacial energy alignment, realize environment-friendly water/alcohol processing, induce the upper active layer to form order morphology and enhance the PCE of PSCs. Based on P3HT–PC61BM active layer, the PCE of the device based on PNSO3Na CIL was dramatically enhanced from 0.8 to 3.7% compared to the bare ITO device.

La/Sm-doped Strontium-ferrite/poly-m-toluidine Composites Obtained by In Situ Polymerization

La/Sm-doped strontium-ferrite/poly-m-toluidine) (PMT) composites were synthesized by in-situ chemical polymerization of m-toluidine in the presence of La/Sm-doped strontium-ferrite particles. Structural, morphological and electro-magnetic properties of nanocomposites were performed by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), four-probe conductivity tester and vibrating sample magnetometer (VSM). The results of XRD indicated that La3+ and Sm3+ had entered into the lattice of strontium ferrite. FTIR spectra demonstrated that there were interactions between ferrite particles and PMT. SEM studies showed that the composites presented the core-shell structure. Under applied magnetic field, nanocomposite exhibited the hystereric loops of the ferromagnetic behavior. The saturation magnetization and coercivity of nanocomposites varied with the content of (LaSm)(0.06)SrFe(11.88)O(19)particles.