Synthesis, Properties, and Solar Cell Performance of Poly(4‐(p‐alkoxystyryl)thiazole)s

Abstract

A series of polythiazoles (PvTzs) featuring conjugated styryl sidechains equipped with different solubilizing p‐alkoxy‐groups (OR, R = n‐octyl, n‐dodecyl, 2‐ethylhexyl, 2‐hexyldecyl) is prepared by Negishi‐coupling polycondensation. Soluble material with number‐average molecular weights of up to Mn = 8.5 kDa (polydispersity (PDI) = 1.3, degree of polymerization (DPn) ≈ 20) is obtained, with a head‐to‐tail content of the PvTzs of ≈77%, as estimated from comparison with reference polymers. The polymers exhibit optical absorption properties similar to their polythiophene analogues, while their electrochemical characterization shows a significant stabilization of their frontier orbital levels. Fluorescence measurements indicate that upon excitation of the electron rich alkoxystyryl side‐chains charge transfer onto the more electron deficient polythiazole backbone occurs. This finding is corroborated by density functional theory (DFT) calculations on oligomeric model systems, which also consistently reproduce the optical properties observed for the polymers. The potentialities of these materials for applications in organic electronics can be demonstrated by their use as donor materials in organic photovoltaic cells, which exhibit higher open circuit voltages (VOC, up to 0.86 V) than P3HT‐ or analogous polythiophene‐based cells (VOC = 0.5–0.6 V).

Recent advances in n-type and ambipolar organic semiconductors and their multi-functional applications

“…Apart from Suzuki and Stille reactions, other reaction types can also be used in electron deficient organic semiconductor synthesis, such as the Negishi cross-coupling 73 (C–ZnR/C–X), Kumada cross-coupling 74,75 (nickel-catalyzed coupling between the Grignard reagent and aryl halides), and Heck reactions 76,77 (palladium-catalyzed coupling between olefins and aryl halides).…”

Recent Advances in Organic Photovoltaic Materials Based on Thiazole‐Containing Heterocycles

“…In 2018, Pammer et al synthesized a series of polythiazoles whose HOMO levels were deeper than those of P3HT. [ 30 ] PvTz8:PC 61 BM‐based OSCs exhibited a PCE of 0.66% with a V OC of 0.77 V.…”

Structural Engineering in Polymer Semiconductors with Aromatic N-Heterocycles

“…These experimental results imply the reduced reactivity upon oligomer homologation of thiazole derivatives. This is likely the reason why reports about poly­(thiazole) are limited. − …”