Simple and Versatile Molecular Donors for Organic Photovoltaics Prepared by Metal‐Free Synthesis

Abstract

Donor-acceptor molecules (D-π-A) built by connecting a diphenylhydrazone block to a dicyanovinyl acceptor group via various thiophene-based π-conjugating spacers (1-5) were synthesized from mono- or dialdehydes by a simple metal-free procedure. Cyclic voltammetry and UV/Vis absorption spectroscopy show that the extension and/or increase of the donor strength of the spacer produces a decrease of the HOMO and LUMO energy level, a red shift of the absorption spectrum and an increase of the molecular absorption coefficient. Compared to solutions, the optical spectra of spin-cast thin films of compounds 1-3 show a broadening and red shift of the absorption bands, consistent with the formation of J-aggregates. In contrast the blue shift observed for the EDOT-containing compounds 4 and 5 suggests the presence of H-aggregates. Solution-cast and vacuum-deposited films of donors 1-5 were evaluated in solar cells with fullerene C60 as acceptor. A power-conversion efficiency among the highest reported for bilayer devices of basic configuration was obtained with compound 2. On the other hand, the results obtained with 4 and 5 suggest that the presence of EDOT in the structure can have deleterious effects on the organization and performances of the donor material.

Recent Advances in Ambipolar Transistors for Functional Applications

“…These improvements finally gave rise to excellent charge carrier mobilities of 0.015 (holes) and 0.168 cm 2 V −1 s −1 (electrons) under ambient conditions. Recently, researchers also explored the novel ambipolar D–A small molecules by attaching different π‐conjugating spacers including thiophene, bithiophene, benzothiophene, benzothiadiazole and thieno[3,2‐ b ]thiophene (TT) to various common groups for instance DPP, NDI derivatives and isoindigo to regulate the intermolecular interactions and energy band structures . Lin et al presented DPP‐derivatives with an A–D–A–D–A construction incorporating DPP core unit and planar bithiophene or TT electron donors .…”

Simple donor-acceptor molecule with long exciton diffusion length for organic photovoltaics

“…However, SMs which show the best performance in OSCs are typically hard to synthesize (8)(9)(10)(11)(12)(13)(14) synthetic steps), which lowers the overall yield to 3-15% [11,[16][17][18][19]. The approach to simplifying the synthetic process was thoroughly explored by Roncali and coworkers [9,16,[20][21][22][23][24][25][26][27][28] who designed a number of easy-to-synthetize SMs based on triphenylamine (TPA) as donor and dicyanovinyl (DCV) as acceptor blocks.…”

CuAAC-Based Assembly and Characterization of a New Molecular Dyad for Single Material Organic Solar Cell

“…28 The aldehyde moieties were then installed by the successive deprotonation and quenching of the lithiated intermediate with dry N,N-dimethylformamide (DMF). Thereafter, the resulting compound (4) was engaged in a reaction with only one equivalent of N,N-diphenylhydrazine in diluted media yielding the mono hydrazone based aldehyde 5 [30].…”