Surface Energy Modification of Semi-Random P3HTT-DPP

Abstract

Alkyl solubilizing side chains on conjugated polymers can serve as a handle for modifying polymer properties. Recently, oligo-ether and semifluoro alkyl side chains were utilized to tune the surface energy of random P3HT-based polymers without changing the optical and electronic properties. Here, this method is applied to semirandom poly(3-hexylthiophene-thiophene-diketopyrrolopyrrole) (P3HTT-DPP) and the subsequent polymer device, optical, electronic, structural, and thermal properties are characterized. P3HTMETT-DPP, bearing oligo-ether side chains, exhibited higher crystallinity, closer lamellar packing, and lower temperature thermal transitions. P3HTFHTT-DPP, featuring semifluoro alkyl side chains, presented reduced crystallinity, greater lamellar packing distances, and higher temperature thermal transitions. P3HTMETT-DPP performed similarly to P3HTT-DPP under identical processing conditions, whereas P3HTFHTT-DPP had greatly reduced J SC due to lower polymer concentration necessitated by solubility.

Exploring the influence of acceptor content on semi‐random conjugated polymers

“…As a promising alternative approach, semi‐random conjugated polymers have attracted significant attention in the past five years . Our group has developed regioregular poly(3‐hexylthiophene) (rr‐P3HT or simply P3HT) based semi‐random copolymers where a small amount of acceptor units (5–15%) were incorporated into the polymer backbone in a randomized fashion .…”

Preparation of semi‐alternating conjugated polymers using direct arylation polymerization (DArP) and improvement of photovoltaic device performance through structural variation

“…However, the d 100 spacing for P6 does slightly decrease and the intensity of the peak dwarfs that of the other polymers. This is attributable to an increased degree of crystallinity for P6 , which is likely due to the same alkyl substituent for both the alkoxy phenylene donor and the DTDPP acceptor providing greater structural symmetry . The random polymers incorporating DTDPP ( P8 and P9 ), do show lower degrees of crystallinity and very broad endotherms and exotherms (see Supporting Information), but the inclusion of DTDPP into these structural motifs undoubtedly provides the low levels of crystallinity observed, especially when compared with the random polymer incorporating DTTPD alone ( P4 ).…”

Design of Random and Semi‐Random Conjugated Polymers for Organic Solar Cells

“…Notably, the availability of polar AB functionalized monomers (hexyloxy, ester, and oligoether) via an organo‐magnesium intermediate also facilitated new achievements with semi‐random donor‐acceptor polymers. Small incorporations of 3HOT, 3HET, and MET monomers in place of some of the 3HT feed ratio offered another handle for finely tuning electronic and optical properties of semi‐random D‐A polymers . These polymers are discussed in the following section.…”

“…Small incorporations of 3HOT, 3HET, and MET monomers in place of some of the 3HT feed ratio offered another handle for finely tuning electronic and optical properties of semi-random D-A polymers. [25,55,56] These polymers are discussed in the following section.…”

“…[70] Accordingly, our group utilized the surface energy modification method described for P3HT copolymers, P3HT-co-FHT and P3HT-co-MET (Scheme 7), to prepare a set of semi-random P3HTT-DPP polymers (Scheme 10). [56] Surface energy could be tuned up to 25.7 mN m -1 or down to 15.0 mN m -1 simply by replacing half of the 3-hexylthiophene feed ratio with MET or FHT monomers, respectively. Again, optical and electronic properties were nearly identical ( Table 6).…”