Rational Design of Diketopyrrolopyrrole-Based Small Moleculesas Donating Materials for Organic Solar Cells

Abstract

A series of diketopyrrolopyrrole-based small molecules have been designed to explore their optical, electronic, and charge transport properties as organic solar cell (OSCs) materials. The calculation results showed that the designed molecules can lower the band gap and extend the absorption spectrum towards longer wavelengths. The designed molecules own the large longest wavelength of absorption spectra, the oscillator strength, and absorption region values. The optical, electronic, and charge transport properties of the designed molecules are affected by the introduction of different π-bridges and end groups. We have also predicted the mobility of the designed molecule with the lowest total energies. Our results reveal that the designed molecules are expected to be promising candidates for OSC materials. Additionally, the designed molecules are expected to be promising candidates for electron and/or hole transport materials. On the basis of our results, we suggest that molecules under investigation are suitable donors for [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and its derivatives as acceptors of OSCs.

A comparative analysis of symmetric diketopyrrolopyrrole‐cored small conjugated molecules with aromatic flanks: From geometry to charge transport

“…It can be concluded that the heteroatom does not change the reorganization energies. Noteworthy, that Jin and Wang obtained similar values for the reorganization energies of similar DPP compounds with side chains and additional thiophene rings: with Fu flanks 0.153 and 0.301 eV for and , respectively, and with Th flanks 0.160 and 0.293 eV for and , respectively.…”

“…Here, we can mention only a few theoretical works devoted to structural, electronic and CT properties of DPP with thiophene or furan flanks . As an auxiliary method, the modeling usually supports the experiment with a “standard analysis” of conjugated backbones such as ground state geometries, frontier molecular orbitals, optical and electronic band gaps, torsion potentials, and less often excited states .…”

“…It was found that the double bond stretching and twisting motions related to the dithienyl‐DPP unit mainly cause the orbital localization, modulate the transfer integrals and affect the mobility in the conjugated chains. Also, Jin and Wang have studied the correlation between the chemical composition, the crystalline packing and the microscopic charge transport of DPP‐Th conjugated molecules. For the first time, DPPs flanked with thiophenes were described fully theoretically using a combination of ab initio techniques and the crystal packing prediction algorithms .…”

“…Also, Jin and Wang have studied the correlation between the chemical composition, the crystalline packing and the microscopic charge transport of DPP‐Th conjugated molecules. For the first time, DPPs flanked with thiophenes were described fully theoretically using a combination of ab initio techniques and the crystal packing prediction algorithms . Recently, we have studied the CT in the crystalline samples of DPP cores flanked with bithiophene fragments using a multiscale simulation scheme .…”

Computational study of structure, electronic, and microscopic charge transport properties of small conjugated diketopyrrolopyrrole‐thiophene molecules

“…The reorganization energy represents the relaxation energy on the charge transfer, when going from neutral to charged states and vice versa, and consists of two terms, the inner contribution λ i determined by nuclear rearrangement alone, and the outer contribution λ o , which takes into consideration the effects of surrounding medium. Despite the fact, that the second term can be essential, it is usually excluded from a consideration, as it was done for some DPP‐thiophene derivatives . The current theoretical treatment of electronic coupling involves its calculation using one of the computational schemes to detect the conductive pathways in the crystals.…”