Free Charge Carriers in Homo-Sorted π-Stacks of Donor–Acceptor Conjugates

Abstract

Inspired by the high photoconversion efficiency observed in natural light-harvesting systems, the hierarchical organization of molecular building blocks has gained impetus in the past few decades. Particularly, the molecular arrangement and packing in the active layer of organic solar cells (OSCs) have garnered significant attention due to the decisive role of the nature of donor/acceptor (D/A) heterojunctions in charge carrier generation and ultimately the power conversion efficiency. This review focuses on the recent developments in emergent optoelectronic properties exhibited by self-sorted donor-on-donor/acceptor-on-acceptor arrangement of covalently linked D–A systems, highlighting the ultrafast excited state dynamics of charge transfer and transport. Segregated organization of donors and acceptors promotes the delocalization of photoinduced charges among the stacks, engendering an enhanced charge separation lifetime and percolation pathways with ambipolar conductivity and charge carrier yield. Covalently linking donors and acceptors ensure a sufficient D–A interface and interchromophoric electronic coupling as required for faster charge separation while providing better control over their supramolecular assemblies. The design strategies to attain D–A conjugate assemblies with optimal charge carrier generation efficiency, the scope of their application compared to state-of-the-art OSCs, current challenges, and future opportunities are discussed in the review. An integrated overview of rational design approaches derived from the comprehension of underlying photoinduced processes can pave the way toward superior optoelectronic devices and bring in new possibilities to the avenue of functional supramolecular architectures.

Quantum Dynamics of Electron–Hole Separation in Stacked Perylene Diimide-Based Self-Assembled Nanostructures

“…The DA block co-oligomer system under study, illustrated in Figure , belongs to a class of covalently bound DA dyad assemblies combining PDI acceptor moieties with various types of donor units. − ,, Architectures that rely on the self-assembly of such co-oligomers are promising since they should permit the controlled formation of e–h pairs followed by efficient carrier transport along 1D or two-dimensional (2D) conductive channels. In practice, though, these approaches have mostly been limited to power conversion efficiencies (PCE) of 1–2%, inferior to conventional bulk heterojunction architectures.…”

“…In the present study, we carry out a full quantum dynamical analysis of charge separation in mesomorphic self-assembled nanostructures composed of conjugated donor–acceptor block co-oligomers. Conjugated block copolymer photovoltaics have emerged as a route toward highly controlled heterojunction architectures. − Specifically, the mesomorphic DA block co-oligomer nanostructures under consideration in the present work are based on PDIs combined with fluorene-thiophene-benzothiadiazole donor units. Such self-assembled nanostructures have been described in refs − and were characterized by electron diffraction (ED) studies .…”

Chromophoric Dendrimer-Based Materials: An Overview of Holistic-Integrated Molecular Systems for Fluorescence Resonance Energy Transfer (FRET) Phenomenon

“…This requires the continuous development and synthesis of new advanced synthetic materials to harvest photon energy, eventually converting it and efficiently transferring it to other active sites. The efficiency of this process depends on the spatial distance (e.g., between donor-acceptor sites) of the transfer of light energy to the site where it can be transduced into other forms of energy [122][123][124].…”

Solvent dielectric delimited nitro–nitrito photorearrangement in a perylenediimide derivative

“…22 It is rationalized, that the photodissociation step is probably characterized by a nitritoaromatic intermediate (-ONO), whose experimental characterization is still in debate and therefore not observed hitherto. 11 Our persistent efforts in understanding the novel non-covalent interactions in unique chromophoric architectures 23,24 and deciphering the diverse photoexcited state processes in multichromophoric assemblies, [25][26][27][28] motivated us to dwell into the realm of linkage isomers, thereby unravelling the photoexcited mechanism responsible for the isomerization. This report highlights the first unequivocal evidence of linkage isomerism in a nitroperylenediimide chromophore.…”