Oligo- and poly(fullerene)s for photovoltaic applications: Modeled electronic behaviors and synthesis

Abstract

The atom transfer radical addition polymerization (ATRAP) of fullerene to give poly(fullerene)s (PFs) for organic electronics is explored. Quantum chemistry maps the expected electronic behavior of PFs with respect to common electron acceptors, namely fullerene, phenyl‐C61‐butyric acid methyl ester and its bis‐adduct, and mono‐ and bis‐indine‐fullerene derivatives. Surprisingly, it is found that PFs should demonstrate electron affinities and LUMO energy levels closer to the bis‐derivatives than the mono‐adducts, even though only one C60 double‐bond is used in PF chain formation. A self‐consistent library of PFs is synthesized and a correlation between structural characteristics and molecular weights is found. While comonomers with –OC16H33 linear side‐chains lead to the highest known ATRAP molecular weights of 21000 g mol−1, like‐for‐like, branched side‐chains permit syntheses of higher molecular weights and more soluble polymers. Of the series, however, PFs with ‐OC12 side‐chains are expected to be of the greatest interest for opto‐electronic applications due to their ease of handling and highest regioregularity. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 1345–1355

In Situ Generation of Fullerene from a Poly(fullerene)

“…The samples that were used in this study are the same as those characterized (GPC, NMR, UV–visible, cyclic voltammetry, etc.) in detail in reference , and accordingly the same code for each structure is used.…”

“…Steric exclusion created by the first pair of additions, coupled with a favorable ratio of reagents, tends to limit the attack of more comonomers to the C 60 , making it possible to form linear oligomers and polymers. Further details are given in reference .…”

“…We also calculated that analogous ATRAP‐PFs based on C 60 , that is, with the structure poly{(fullerene)‐ alt ‐[1,4‐bis(methyl)‐2,5‐di(alkyloxy)benzene]} (PFBMB) would have electronic properties similar to those of PCBM. Therefore, we prepared a small library of PFBMBs to understand how variations in side chains influence the formation of oligomers and polymers . We were interested to see whether these new C 60 based PFBMBs would also stabilize devices.…”

Review: materials and modelling for organic photovoltaic devices

“…In our own work, we have found that by using fullerene as a comonomer in alternating main‐chain polymers, it is possible to raise the position of the LUMO by around 0.5 eV with respect to PCBM by way of the type of polyaddition and comonomer used, as shown in Fig. 14 77–81 . However, these variations still remain little in comparison to the so‐called non‐fullerene acceptors.…”

Towards the synthesis of poly(azafulleroid)s: main chain fullerene oligomers for organic photovoltaic devices

“…Prior methods included Diels–Alder chemistry, methano‐bridges and an elegant tether‐directed pre‐modification of C 60 , but these also gave crosslinking, intractable products or required multi‐step preparative chemistry, respectively. An attempt to resolve this was made using atom transfer radical addition polymerization as the reaction is based on radical bis‐additions around just one C 60 1,4‐phenylic ring . One disadvantage of this system, though, was the high amounts of CuBr required, leading to metal impurities of which even trace amounts can be detrimental to device performances .…”