Molecular Weight Engineering in High‐Performance Ambipolar Emissive Mesopolymers

Mesopolymers with high solubility, free of structural defects, and negligible batch‐to‐batch variation open a new avenue for organic optoelectronics. Organic light emitting transistors that combine the functions of organic light‐emitting diodes and organic field‐effect transistors. However, charge transport ability and light emitting strength are contradictory within one conjugated polymer. Herein, three low‐molecular‐weight mesopolymers with thienopyrroledione–benzothiadiazole repeating units (meso‐TBTF) were obtained. The mesopolymers show strong solid‐state emission and high ambipolar carrier mobility. The molecular weights of meso‐TBTF can be tuned by polymerization temperature. The mesopolymers have photoluminescence quantum yields (PLQY) of about 50 % in solution and 10 % in solid state. Polymer light emitting diodes of this material are fabricated to explore its potential use in optoelectronic devices. Molecular weight engineering of red‐emissive mesopolymer with no detectable homo‐coupling defects, fine‐tuned energy level and better bipolar mobility was carried out. OFET and OLED based on the materials mark application potential in optoelectronic devices.