Cheng-Kang Mai

Tertiary amines covalently tethered to electron-deficient aromatic molecules by alkyl spacers enable solid-state n-doping.

A one-pot synthesis of random semicrystalline/amorphous multiblock copolymers is demonstrated via acyclic diene metathesis (ADMET) polymerization of α,ω-divinyl-terminated telechelic polyolefins.

We report the synthesis of a series of water soluble anionic narrow band-gap conjugated polyelectrolytes with a varied density of the ionic functional groups.

We report the demonstration of antimicrobial conjugated polyelectrolytes (CPEs) with high NIR absorbance for selective and efficient photothermal killing of bacteria over mammalian cells. The antimicrobial CPE possessing quaternary ammonium (QA) terminated side chains (P1) shows higher binding preference and increased dark toxicity towards Gram-positive and Gram-negative bacteria over mammalian cells. Bestowed by π-conjugated backbones, P1 exhibits a high molar absorptivity of 39.8 L g⁻¹ cm⁻¹ at 808 nm with an efficient photothermal conversion efficiency of 33 ± 1%. Upon 808 nm laser irradiation, P1 shows enhanced bactericidal effects, but not to mammalian cells. Although the anionic CPE counterpart with the same polymer backbone but sulfonate terminated side chains (P2) possesses a similar photothermal conversion ability, it exhibits much lower antibacterial effects due to its low binding affinity. This study thus reveals that bacteria–CPE electrostatic interactions play a major role in bacterial recognition, although hydrophobic interactions also contribute.

Organic–inorganic hybrid perovskite materials offer the potential for realization of low-cost and flexible next-generation solar cells fabricated by low-temperature solution processing. Although efficiencies of perovskite solar cells have dramatically improved up to 19% within the past 5 years, there is still considerable room for further improvement in device efficiency and stability through development of novel materials and device architectures. Here we demonstrate that inverted-type perovskite solar cells with pH-neutral and low-temperature solution-processable conjugated polyelectrolyte as the hole transport layer (instead of acidic PEDOT:PSS) exhibit a device efficiency of over 12% and improved device stability in air. As an alternative to PEDOT:PSS, this work is the first report on the use of an organic hole transport material that enables the formation of uniform perovskite films with complete surface coverage and the demonstration of efficient, stable perovskite/fullerene planar heterojunction solar cells.

Selective doping of single-walled carbon nanotubes can be achieved by varying pendant ionic functionalities of conjugated polyelectrolytes.

Rational materials design and interface engineering are both essential to realize a high performance for tandem cells. Two identical bulk heterojunctions are connected in series using novel interconnection layers combining pH-neutral conjugated polyelectrolytes and a thin film of ZnO nanoparticles by a solution process. The best performing tandem cells achieve a power conversion efficiency of 11.3%, with 25% enhancement in efficiency compared with single cells, which arises primarily from the increased light absorption.