New conjugated molecular scaffolds based on [2,2]paracyclophane as electron acceptors for organic photovoltaic cells

Abstract

Two conjugated molecules with a [2,2]paracyclophane core were designed as non-fullerene electron acceptors for photovoltaic cells. Using as the donor, a high power conversion efficiency (2.69%) is achieved for the blending thin film of with , which is relatively high for solution-processed OPVs based on small molecular non-fullerene acceptors and as the electron donor.

Homochiral [2.2]Paracyclophane Self‐Assembly Promoted by Transannular Hydrogen Bonding

“…[1] The rigid connectivity and positioning of its "bent and battered benzene rings" [2] are the basis for through-space (transannular p-p)a nd through-bond [s(bridge)-p(deck)] interactions [3] which strongly perturb the chemical, optical, and electronic properties of the molecule.The synthetic chemistry of pCp is quite mature and allows functional groups to be precisely positioned on the rings and bridges [2,4] -two common ring substitution patterns are shown in Figure 1b. [11] Theprospect of delocalized electronic states emerging for extended p-stacked cyclophanes dates back to the seminal work of the groups of Chow, [12] Misumi, [13] and Staab, [14] whose tediously prepared multitiered structures (e.g., Figure 1c) showed, for example,l onger wavelength absorption and emission maxima upon increasing the number of intervening benzene rings.T he single-molecule conductance of such constructs has only recently been measured. [11] Theprospect of delocalized electronic states emerging for extended p-stacked cyclophanes dates back to the seminal work of the groups of Chow, [12] Misumi, [13] and Staab, [14] whose tediously prepared multitiered structures (e.g., Figure 1c) showed, for example,l onger wavelength absorption and emission maxima upon increasing the number of intervening benzene rings.T he single-molecule conductance of such constructs has only recently been measured.…”

Design of Diketopyrrolopyrrole (DPP)‐Based Small Molecules for Organic‐Solar‐Cell Applications

“…[2,2]paracyclophane framework was introduced to construct nonfullerene electron acceptors by Zhang et al, in which four DPP moieties were linked at different positions ( para ‐ or meta ‐ position) of [2,2]paracyclophane ( j16 and j17 ). Meanwhile, they changed the end‐capped groups on the DPP moiety with trifluorophenyl (i.e., j16a and j16b , j17a and j17b ), to finely tune frontier energy levels.…”

“…j15 was synthesized as a reference, which possessed a close HOMO/LUMO energies with respect to those of j16b . Using P3HT as the donor, j15 led to poor photovoltaic performance with a PCE of 0.90%, whereas a high PCE of 2.69% was achieved for the blending thin film of j16b with P3HT . A PCE of 1.84% was obtained for j17b ‐based device after thermal annealing .…”

A Nonfullerene Small Molecule Acceptor with 3D Interlocking Geometry Enabling Efficient Organic Solar Cells

“…Despite the widespread use of fullerene acceptors, these acceptors tend to exhibit several drawbacks, including poor photochemical stability in air, weak absorption of visible light, limited energy level variability, and high production costs . These limitations have driven researchers to develop nonfullerene acceptors including small molecules and polymers designed to replicate the favorable electronic properties of fullerenes while overcoming their aforementioned deficiencies. Thus far, the PCEs of nonfullerene OSCs have exceeded 6% …”