Positron Annihilation Spectroscopic Investigation on the Origin of Temperature-Dependent Electrical Response in Methylammonium Lead Iodide Perovskite.

Organic-inorganic hybrid perovskite has appeared as one of the leading materials for realizing solution-based high-performing optoelectronic devices. The charge transport properties in this class of material are quite intriguing and still need to be carefully investigated. The temperature-dependent electrical property of methylammonium lead iodide (CHNHPbI) has been investigated by employing positron annihilation spectroscopy (PAS), which unambiguously reveals the gradual formation of open volume defects with the enhancement in temperature.

Is the Chemical Strategy for Imbuing "Polyene" Character in Diketopyrrolopyrrole-Based Chromophores Sufficient for Singlet Fission?

In this work, we have rationally designed and synthesized a novel thiophene-diketopyrrolopyrrole (TDPP)-vinyl-based dimer. We have investigated the optical and electronic properties and have probed the photophysical dynamics using transient absorption to investigate the possibility of singlet exciton fission. These revealed extremely rapid decay to the ground state (<50 ps), which we confirm is due to intramolecular excitonic processes rather than large-scale conformational change enabled by the vinyl linker.

Effect of Chalcogens on Electronic and Photophysical Properties of Vinylene-Based Diketopyrrolopyrrole Copolymers.

Three vinylene linked diketopyrrolopyrrole based donor-acceptor (D-A) copolymers have been synthesized with phenyl, thienyl, and selenyl units as donors. Optical and electronic properties were investigated with UV-vis absorption spectroscopy, cyclic voltammetry, near edge X-ray absorption spectroscopy, organic field effect transistor (OFET) measurements, and density functional theory (DFT) calculations. Optical and electrochemical band gaps decrease in the order phenyl, thienyl, and selenyl.

Modulation of electronic and self-assembly properties of a donor-acceptor-donor-based molecular materials via atomistic approach.

The performance of molecular materials in optoelectronic devices critically depends upon their electronic properties and solid-state structure. In this report, we have synthesized sulfur and selenium based (T4BT and T4BSe) donor-acceptor-donor (D-A-D) organic derivatives in order to understand the structure-property correlation in organic semiconductors by selectively tuning the chalcogen atom. The photophysical properties exhibit a significant alteration upon varying a single atom in the molecular structure.

Herringbone to cofacial solid state packing via H-bonding in diketopyrrolopyrrole (DPP) based molecular crystals: influence on charge transport.

The mono-alkylation of DPP derivatives leads to cofacial π-π stacking via H-bonding unlike their di-alkylated counterparts, which exhibit a classical herringbone packing pattern. Single crystal organic field-effect transistor (OFET) measurements reveal a significant enhancement of charge carrier mobility for mono-hexyl DPP derivatives.

Self-assembly and catalytic activity of metal nanoparticles immobilized in polymer membrane prepared via layer-by-layer approach.

Densely packed nanoparticles distributed in a stable and robust thin film is a highly preferred system for utilizing the various applications of nanoparticles. Here, we report covalent bond mediated layer-by-layer (LbL) self-assembled thin films of nanoparticles embedded in polymer membrane. Polymer with complementary functional group is utilized for fabrication of thin film via covalent bonding.

Multilayer single-component thin films and microcapsules via covalent bonded layer-by-layer self-assembly.

Fabrication of single-component multilayer thin films still remains a challenging task via the layer-by-layer (LbL) approach. In this communication, we report the self-assembly of single-component multilayer thin films on flat and colloidal substrates through glutaraldehyde mediated covalent bonding.