The ability of quantum simulations to predict the electronic structure at donor/acceptor interfaces and correlate it with the quantum efficiency of organic solar cells remains a major challenge. The need to describe with increased accuracy electron-electron and electron-hole interactions, while better accounting for disorder and environmental screening in realistic interfaces, requires significant progress to improve both the accuracy and computational efficiency of available quantum simulation methods. In the present study, the results of different ab initio techniques are compared, namely time-dependent density functional and many-body perturbation theories, with experimental data on three different polymer/fullerene heterojunctions. It is shown that valuable information concerning the thermodynamic drive for electron-hole dissociation or recombination into triplets can be obtained from such calculations performed on model interfaces. In particular, the ability of these approaches to reproduce the Veldman and co–workers classification of the three studied interfaces is discussed, showing the success and limits of state-of-the-art ab initio techniques.

The structural organization of three different families of semicrystalline π-conjugated polymers is reported (poly(3-hexylthiophene) (P3HT), poly[2,6-(4,4-bis-alkyl-4H-cyclopenta-[2,1-b;3,4-b0]-dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)](cyclopentadithiophene-benzothiadiazole) (CDT-BTZ) and poly(N,N"-bis-2-octyldodecylnaphtalene-1,4,5,8-bis-dicarboximide-2,6-diyl-alt-5,5–2,2-bithiophene (P(NDI2OD-T2))). These have triggered significant interest for their remarkable charge-transport properties. By performing molecular mechanics/dynamics simulations with carefully re-parameterized force fields, it is illustrated in particular how the supramolecular organization of these conjugated polymers is driven by an interplay between the length and nature of the conjugated monomer unit and the packing of their alkyl side chains, and to what extent it impacts the charge-carrier mobility, as monitored by quantum-chemical calculations of the intermolecular hopping transfer integrals. This Progress Report is concluded by providing generic guidelines for the design of materials with enhanced degrees of supramolecular organization.

A bottom-up approach toward stable and monodisperse segments of graphenes with a nitrogen-doped zigzag edge is introduced. Exemplified by the so far unprecedented dibenzo-9a-azaphenalene (DBAPhen) as the core unit, a versatile synthetic concept is introduced that leads to nitrogen-doped zigzag nanographenes and graphene nanoribbons.

Eine Bottom-up-Methode zur Synthese stabiler und monodisperser Graphensegmente mit Stickstoff-dotierten Zickzackkanten wird vorgestellt. Auf Grundlage des bisher unbeschriebenen Dibenzo-9a-azaphenalens (DBAPhen) als molekularer Baustein wird ein allgemein anwendbares Konzept zur Synthese ausgedehnter Nanographene und Nanographenstreifen mit Stickstoff-dotierten Zickzackkanten eingeführt.

We have prepared a new borazine derivative that bears mesityl substituents at the boron centers and displays exceptional chemical stability. Detailed crystallographic and solid-state fluorescence characterizations revealed the existence of several polymorphs, each of which showed different emission profiles. In particular, a bathochromic shift is observed when going from the lower- to the higher-density crystal. Computational investigations of the conformational dynamics of borazine 1 in both the gas phase and in the solid state using molecular dynamics (MD) simulations showed that the conformation of the peripheral aryl groups significantly varies when going from an isolated molecule (in which the rings are able to flip over the 90° barrier at RT) to the crystals (in which the rotation is locked by packing effects), thus generating specific nonsymmetric intermolecular interactions in the different polymorphs. To investigate the optoelectronic properties of these materials by fabrication and characterization of light-emitting diodes (LEDs) and light-emitting electrochemical cells (LECs), borazine 1 was incorporated as the active material in the emissive layer. The current and radiance versus voltage characteristics, as well as the electroluminescence spectra reported here for the first time are encouraging prospects for the engineering of future borazine-based devices.