Diketopyrrolopyrrole-based single molecules in photovoltaic technologies

Abstract

In this revision we have highlighted the most relevant works from the last few years involving diketopyrrolopyrroles (DPPs) as single molecules in organic photovoltaic devices. We have given a tour...

Structure–property relationships of diketopyrrolopyrrole- and thienoacene-based A–D–A type hole transport materials for efficient perovskite solar cells

“…[21][22][23] Along with their ease of synthesis and bathochromic absorption, previously reported DPP-based materials displayed novel properties such as strong visible absorption, high co-planarity, good photochemical stability and excellent charge carrier mobility, attributed to the advantages of the DPP acceptor units. 21,22,[24][25][26][27][28][29][30][31][32] Moreover, the insertion of a planar aromatic p-bridge between the two DPP acceptor units has been demonstrated to be the most tested and proven strategy for extending the effective conjugation length, enhancing the backbone planarity, regulation of the frontier molecular orbital (FMO) energy levels and acquiring high charge mobilities. [23][24][25]28,31,33,34 Besides, similar to the molecular engineering of the organic semiconducting materials through optimization of the conjugated backbone, atomic substitution, and flexible side chains, the introduction of fused heteroarenes in conjugated backbone has shown enhanced charge-carrier mobilities and they are theoretically predicted to show narrower energy bandgaps relative to smaller acenes and polycyclic aromatic compounds with an identical number of aromatic groups due to an increased effective conjugation length and a concomitant decrease in reorganization energy in these species.…”

A′–A–π–D–π–A–A′ extended small-molecule photovoltaic donor based on fluorene-diketopyrrolopyrrole with an end-group fluorination effect

“…28 The solubility of DPP-based molecules could be increased by alkyl substitution at the 2,5-position of the lactam nitrogen, which is conducive to the formation of good film morphology with fullerene acceptors. 29 Based on these significant advantages, DPP units have great potential in the design of organic photovoltaic materials.…”

Using diketopyrrolopyrroles to stabilize double excitation and control internal conversion

“…They strongly absorb visible light, show significant electron-withdrawing effects, and possess high electron mobility. [8][9][10][11][12] Due to these properties, DPPs are often used as an electron-acceptor unit to design optoelectronic devices 13,14 such as new push-pull polymers, 15,16 organic light-emitting diodes, 17 and more recently, singletfission chromophores. 8,18,19 Motivated by the design of new intramolecular singlet-fission materials, Mukhopadhyay et al 20 proposed a combination of a thiophene-DPP derivative (with charge-transfer (CT) character) with a vinyl linker (polyene character) (Figure 1b).…”

“…The effect of DPP units on the performance of photovoltaic materials and the closed or openshell nature of DPP's ground state has already been investigated. 8,12,21,22 Given the large size of these molecules, discussions about their electronic structure properties are often based on the density functional theory (DFT) HOMO-LUMO gaps or linear-response time-dependent DFT (TDDFT) excitations. 19,21,23,24 Nevertheless, depending on the molecular architecture, DFT and TDDFT cannot correctly describe DPPs derivatives, and characterizing these large molecules' lowlying doubly excited states is still a challenge for computational chemistry.…”