Charge transfer in superbase n-type doping of PCBM induced by deprotonation.

N-type electronic doping of organic semiconductors (OSCs) by using superbase compounds shows high doping efficiency (H. Wei, Z. Cheng, T.

Strain-Induced Indirect-to-Direct Bandgap Transition, Photoluminescence Enhancement, and Linewidth Reduction in Bilayer MoTe.

Two-dimensional (2D) layered materials provide an ideal platform for engineering electronic and optical properties through strain control because of their extremely high mechanical elasticity and sensitive dependence of material properties on mechanical strain. In this paper, a combined experimental and theoretical effort is made to investigate the effects of mechanical strain on various spectral features of bilayer MoTe photoluminescence (PL). We found that bilayer MoTe can be converted from an indirect to a direct bandgap material through strain engineering, resulting in a photoluminescence enhancement by a factor of 2.

Protonation-induced charge transfer and polaron formation in organic semiconductors doped by Lewis acids.

Lewis-acid doping of organic semiconductors (OSCs) opens up new ways of p-type doping and has recently become of significant interest. As for the mechanistic understanding, it was recently proposed that upon protonation of the OSC backbone, electron transfer occurs between the protonated polymer chain and a neutral chain nearby, inducing a positive charge carrier in the latter [B. Yurash, D.

Microscopic Study of Molecular Double Doping.

Double doping, in which a single dopant molecule induces two charge carriers in an organic semiconductor (OSC), was recently experimentally observed and promises to enhance the efficiency of molecular doping. Here we present a theoretical investigation of p-type molecular double doping in a CN6-CP:bithiophene-thienothiophene OSC system. Our analysis is based on density functional theory (DFT) calculations for the electronic ground state.

Atomically Thin Sheets of Lead-Free 1D Hybrid Perovskites Feature Tunable White-Light Emission from Self-Trapped Excitons.

Low-dimensional organic-inorganic perovskites synergize the virtues of two unique classes of materials featuring intriguing possibilities for next-generation optoelectronics: they offer tailorable building blocks for atomically thin, layered materials while providing the enhanced light-harvesting and emitting capabilities of hybrid perovskites. This work goes beyond the paradigm that atomically thin materials require in-plane covalent bonding and reports single layers of the 1D organic-inorganic perovskite [C H N] [BiCl ]Cl. Its unique 1D-2D structure enables single layers and the formation of self-trapped excitons, which show white-light emission.

Density Functional Study on the Intercalation of Fullerenes into AnE-PV Copolymer Layers.

We investigated the intercalation of C into poly(p-anthracene-ethynylene)-alt-poly(p-phenylene-vinylene) copolymers layers by density functional theory calculations in respect of crystal structures and electronic band structures. Based on the experimental observations, we found that the copolymer with branched side chains substituted next to the anthracene units and the linear side chains substituted to the vinylene units has a better tendency to intercalate with C than the reversely substituted copolymer. The calculated electronic band structures of the intercalated phase, featured by flat in-gap states resulting from C molecules, explain the experimentally observed variations of the photocurrent, photoluminescence, and electroluminescence yields with different ratio between PCBM and the two types of copolymers in the ternary blend.

Density Functional Study of Stacking Structures and Electronic Behaviors of AnE-PV Copolymer.

In this work, we report an in-depth investigation on the π-stacking and interdigitating structures of poly(p-anthracene-ethynylene)-alt-poly(p-phenylene-vinylene) copolymer with octyl and ethyl-hexyl side chains and the resulting electronic band structures using density functional theory calculations. We found that in the π-stacking direction, the preferred stacking structure, determined by the steric effect of the branched ethyl-hexyl side chains, is featured by the anthracene-ethynylene units stacking on the phenylene-vinylene units of the neighboring chains and vice versa. This stacking structure, combined with the interdigitating structure where the branched side chains of the laterally neighboring chains are isolated, defines the energetically favorable structure of the ordered copolymer phase, which provides a good compromise between light absorption and charge-carrier transport.

Relativistic effects and the unique low-symmetry structures of gold nanoclusters.

The atomic structures of bare gold clusters provide the foundation to understand the enhanced catalytic properties of supported gold nanoparticles. However, the richness of diverse structures and the strong relativistic effects have posed considerable challenges for a systematic understanding of gold clusters with more than 20 atoms. We use photoelectron spectroscopy of size-selected anions, in combination with first principles calculations, to elucidate the structures of gold nanoclusters in a critical size regime from 55 to 64 atoms (1.