Diketopyrrolopyrroles as Acceptor Materials in Organic Photovoltaics

Abstract

In the search of new electron acceptor, n-type materials for organic solar cells that combine a strong absorption over a broad range with good electrical characteristics, the use of diketopyrrolopyrrole (DPP) derivatives with low reduction potentials is explored. A series of small molecule DPP derivatives is presented and the compounds are tested as electron acceptors in combination with poly(3-hexylthiophene) (P3HT) as the donor material. Working photovoltaic devices are obtained that show a photoresponse in the wavelength region where the DPP molecules absorb. The best device shows a power conversion efficiency of 0.31% in simulated solar light, with a photon-to-electron conversion efficiency of ∼10% up to 700 nm. The efficiency seems to be limited by the coarse morphology of the blend.

Thiophene‐Containing Pechmann Dyes and Related Compounds: Synthesis, and Experimental and DFT Characterisation

“…[13] Unlike Perkins mauveine, Pechmann dyes never became commercial, and after the 1950s became virtually forgotten to a large extent due to the intractable nature of these highly insoluble materials. [10-12, 14, 15] We recognised the similarities of the Pechmann lactams III and such popular organic semiconductor building blocks as N,N-dialkyldipyrollopyrollediones [16] (DPP) and N,N-dialkylnaphthalene-1,8:4,5-tetracarboxydiimides [17,18] (NDI). All of these chromophores have planar, conjugated rings that are highly prone to p-p stacking and carry carboxyl/anhydride functionality that allows facile amidation or imidation; the choice of the alkyl amine dictates the solubility, aggregation and solid-state packing and has a profound influence on organic thin-film transistor (OTFT) and organic photovoltaic (OPV) devices manufactured from organic semiconducting materials.…”

“…Polymers derived from compounds 5-8 at the 5-position of the thiophene rings would thus be structurally similar to P3HT but would have a higher degree of planarity that could, in principle, facilitate good electron/hole transport through the polymer backbone. For analogous polymers derived from Pechmann lactams, poly(thiophene-DPP) [16] and poly(thiophene-NDI) [17] derivatives would be more appropriate structures to compare. B3LYP/DGDZVP modelling showed that the lowest-energy conformation of model thiophene-DPP and thiophene-NDI monomers ( Figure 1, Ar = 2-thienyl, R = isobutyl; the isobutyl group is a realistic model for the long, branched 2-(alkyl 1 )alkyl 2 chains such as 2-octyldodecyl that are attached to the N atoms in order to solubilise actual polymers synthesised and tested in the laboratory) are characterised by thiophene-core dihedral angles of 14 and 648, respectively.…”

Tuning the Optoelectronic Properties of Nonfullerene Electron Acceptors

“…[1] For example, in the case of organic light-emitting diodes,n -type materials play an important role in electron injection and hole blockingt oe nsure that exciton formation occurs in the emitting layer. [1] For example, in the case of organic light-emitting diodes,n -type materials play an important role in electron injection and hole blockingt oe nsure that exciton formation occurs in the emitting layer.…”

A high-performance ambipolar organic field-effect transistor based on a bidirectional π-extended diketopyrrolopyrrole under ambient conditions

“…Explanations for this can be found in the fact that the electrochemical experiment takes place in solution, where stacking of the molecules is absent, resulting in a higher bandgap. 57 However, E g CV is relatively lower compared with E g opt (1.69 eV) in solution, We think that the result have relation to the test concentration in the different environment. Interestingly, the insertion of the phenylene group between DPP-2T and dicyanovinyl moiety, instead of thiophene, resulted in an ~0 .14 eV drop for LUMO and E g compared with those of the previously reported thiophene analogue (LUMO = -3.68 eV, E g CV = 1.69 eV).…”