Achieving
a good balance between the crystallinity and
solubility
is of great importance in the design of π-conjugated polymers.
Here, we synthesized a series of terpolymers in which small fractions
of a planar V-shaped fused ring, triphenyleno[1,2-c:7,8-c′]bis([1,2,5]thiadiazole) (TPTz), are
incorporated into the linear-shaped backbone of a highly crystalline
polymer based on naphtho[1,2-c:5,6-c′]bis([1,2,5]thiadiazole) (NTz), PNTz4T. Due to the “bending”
structure induced by the TPTz unit, the terpolymers had greatly improved
solubility by about 5–9 times compared to the linear-shaped
PNTz4T. In particular, the terpolymers preserved the crystallinity
of PNTz4T to a considerable extent with a higher fraction of face-on
oriented domains in films. As a result, the highly solution-processable
terpolymers exhibited high photovoltaic performances and slightly
outperformed PNTz4T. Our results indicate that the incorporation of
a V-shaped unit into a linearly shaped polymer is a good strategy
to develop π-conjugated polymers with high solubility and crystallinity.