Chinna Bathula

New TIPS-substituted benzo[1,2-b:4,5-b ']dithiophene-based copolymers for application in polymer solar cells

Novel triisopropylsilylethynyl (TIPS)-substituted benzodithiophene-based copolymers, poly[4,8-bis(triisopropylsilylethynyl)benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl-alt-4,6-(2-ethylhexyl-thieno[3,4-b]thiophene-2-carboxylate)] (P1), poly[4,8-bis(triisopropylsilylethynyl)benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl-alt-[4,6-{(1-thieno[3,4-b]thiophen-2-yl)-2-ethylhexan-1-one}] (P2), and poly[4,8-bis(triisopropylsilylethynyl)benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl-alt-4,6-(2-ethylhexyl(3-fluorothieno[3,4-b]thiophene)-2-carboxylate)] (P3), were designed and synthesized for use in polymer solar cells (PSCs). We describe the effects of the different acceptor segment side groups on the optical, electrochemical, field-effect hole mobility, and photovoltaic characteristics of the resulting TIPS-based copolymers. The side groups in the copolymers were found to significantly influence the carrier mobilities and photovoltaic properties of the copolymers. The field-effect mobilities of the holes varied from 9 × 10−5 cm2 V−1 s−1 in P2 to 3 × 10−3 cm2 V−1 s−1 in P1. Under optimized conditions, the TIPS-based polymers showed power conversion efficiencies (PCEs) for the PSCs in the range of 3.16–5.76%. Among the TIPS-based copolymers studied here, P1 showed the best photovoltaic performance, with an open-circuit voltage (Voc) of 0.82 V, a short-circuit current density (Jsc) of 12.75 mA cm−2, a fill factor (FF) of 0.55, and a power-conversion efficiency of 5.76% using a P1:PC71BM blend film as the active layer under AM 1.5G irradiation (100 mW cm−2).

Mild, Simple, and Efficient Method for N-Formylation of Secondary Amines via Reimer–Tiemann Reaction

Abstract A rapid and easy route for the N-formylation of secondary amines using chloroform and sodium ethoxide via dichlorocarbene by the Riemer–Tiemann reaction with excellent yield is reported.

Synthesis and Characterization of Benzodithiophene-Based Copolymers for Polymer Solar Cells

Two novel thieno[3,4-b]pyrazine-based copolymers of the donor-acceptor type, poly[4,8-bis(2-ethylhexyloxy)benzo[1,2-b:4,5-b’]dithiophene-alt-5,7-(2,3-bis-(4-octyl-oxy-phenyl)-thieno[3,4-b]pyrazine)] (P1) and poly[4,8-bis(5-((2-ethylhexylthiophene)-2-yl))benzo[1,2-b:4,5-b’]dithiophene-alt-5,7-(2,3-bis-(4-octyloxy-phenyl)-thieno[3,4-b]pyrazine)] (P2), designed and synthesized by Stille polymerization for use in polymer solar cells. The synthesis, thermal stability, as well as the optical and photovoltaic properties of these polymers are systematically investigated. The polymers were thermally stable up to 290°C, and readily soluble in common organic solvent. Conventional polymer solar cells (PSCs) with the configuration ITO/PEDOT:PSS/polymer:PC71BM/Ca/Al are fabricated. Under optimized conditions, the polymers display power conversion efficiencies (PCEs) for the PSCs in the range 0.28–1.46% under AM 1.5 illumination. Among the studied thienopyrazine-based copolymers, P2 displays a PCE of 1.46% with a short circuit current of 7.61 mA/cm2, an open circuit voltage of 0.43 V, and a fill factor of 0.45 under AM 1.5 illumination.

Responsive Photonic Gels Based on Block Copolymers

Self-assembly of block copolymers has been widely employed in the fabrication of various 1D, 2D and 3D photonic crystals by utilizing the abundant morphologies of block copolymers. When one or both domains of block copolymers were swollen with a significant amount of diluents, they form photonic gels. Comparing with conventional dry polymer or inorganic photonic crystals, photonic gels are very flexible and responsive to the various external stimuli. Especially, polyelectrolyte block copolymer 1D photonic gels swollen with solvents exhibited extremely large tunability of optical properties by chemical, mechanical, thermal, and electrical stimuli. These unique features have been proved to be useful for applications in sensors and displays. In this chapter, we will review the recent works on block copolymer photonic gels. The scope of this review will cover (1) theoretical background of photonic stopbands, (2) fabrication and characterization of photonic gels by self-assembly, and (3) various applications of photonic gels in sensors and displays.