Hydrophilic Conjugated Polymers Prepared by Aqueous Horner–Wadsworth–Emmons Coupling

The synthesis of hydrophilic conjugated polymers typically relies on organometallic coupling methodologies. Here we present an approach to prepare polar poly­(arylene–vinylene)­s (PAVs) in water using the Horner–Wadsworth–Emmons (HWE) reaction. The additional preparation of discrete arylene vinylene (AVs) afforded insight into HWE kinetics and regioselectivity. Nine novel PAVs and AVs were synthesized, characterized by UV–vis absorption and ultraviolet photoelectron spectroscopy, and studied for their utility in sensing and photovoltaic applications

Rapid Visible Light-Mediated Controlled Aqueous Polymerization with In Situ Monitoring

We report a simple procedure for rapid, visible light-mediated, controlled radical polymerization in aqueous solutions. Based on the photoelectron transfer reversible addition–fragmentation chain transfer (PET–RAFT) polymerization, fast chain propagation at room temperature in water was achieved in the presence of reductant and without prior deoxygenation. A systematic study correlating irradiation intensity and polymerization kinetics, enabled by in situ nuclear magnetic resonance spectroscopy, provided optimized reaction conditions. The versatility of this procedure was demonstrated through a rapid triblock copolymer synthesis, and incorporation of water-labile activated esters for direct conjugation of hydrophilic small molecules and proteins. In addition, this technique boasts excellent temporal control and provides a wide range of macromolecular materials with controlled molecular weights and narrow molecular weight distributions

High Efficiency Tandem Thin-Perovskite/Polymer Solar Cells with a Graded Recombination Layer

Perovskite-containing tandem solar cells are attracting attention for their potential to achieve high efficiencies. We demonstrate a series connection of a ∼90 nm thick perovskite front subcell and a ∼100 nm thick polymer:fullerene blend back subcell that benefits from an efficient graded recombination layer containing a zwitterionic fullerene, silver (Ag), and molybdenum trioxide (MoO₃). This methodology eliminates the adverse effects of thermal annealing or chemical treatment that occurs during perovskite fabrication on polymer-based front subcells. The record tandem perovskite/polymer solar cell efficiency of 16.0%, with low hysteresis, is 75% greater than that of the corresponding ∼90 nm thick perovskite single-junction device and 65% greater than that of the polymer single-junction device. The high efficiency of this hybrid tandem device, achieved using only a ∼90 nm thick perovskite layer, provides an opportunity to substantially reduce the lead content in the device, while maintaining the high performance derived from perovskites

N‑Doped Zwitterionic Fullerenes as Interlayers in Organic and Perovskite Photovoltaic Devices

The efficient operation of polymer- and perovskite-based photovoltaic devices depends on selective charge extraction layers that are placed between the active layer and electrodes. Herein, we demonstrate that integration of a tetra-<i>n</i>-butyl ammonium iodide-doped zwitterionic fulleropyrrolidine derivative, C₆₀-SB, as a cathode modification interlayer significantly improves the photovoltaic device performance. Compared to the intrinsic (undoped) zwitterionic material, which is an efficient interlayer itself, the doped interlayers further improve average power conversion efficiencies from 8.37% to 9.68% in polymer-based devices and from 12.53% to 15.31% in perovskite-based devices. Ultraviolet photoelectron spectroscopy revealed that doping increases the interfacial dipole at the C₆₀-SB/Ag interface, i.e., reduces the effective work function of the resultant composite cathode. This effect originates from the population of negative polaron states in C₆₀-SB by extrinsic charges that prevent directional charge transfer from Ag to the integer charge-transfer states in C₆₀-SB, pinning the Fermi level at higher energy. The reduced resistivity of the doped interlayer, as measured by impedance spectroscopy, enables efficient device operation with a broad range of interlayer thicknesses, thus simplifying the solution-based device fabrication process

Highly Photoluminescent Nonconjugated Polymers for Single-Layer Light Emitting Diodes

The design, synthesis, and characterization of solution-processable polymers for organic light emitting diode (OLED) applications are presented. Theoretical calculations were employed to identify a carbazole-pyrimidine based building block as an optimized host material for the emissive layer of an idealized OLED stack. Efficient, free radical homopolymerization and copolymerization with a novel methacrylate-based heteroleptic iridium­(III) complex leads to a library of nonconjugated polymers with pendant semiconductors. Optoelectronic characterization reveals impressive photoluminescence quantum yield (PLQY) values exceeding 80% and single-layer OLEDs show optimal performance for copolymers containing 6 mol % of iridium comonomer dopant