New mesoscopic polymer material system proposed by Hu Wenping, research group, Institute of chemistry, Chinese Academy of Sciences

Organic semiconductor material Including small molecule and polymer materials, small molecule semiconductor materials have precise molecular structure, but it is difficult to achieve large-scale preparation; however, there are many problems in the synthesis of traditional polymer semiconductor materials, such as main chain structure defects and large batch differences, which affect the quality of polymer semiconducting materials and device performance, and seriously restrict its macro synthesis and large-scale device application In order to solve the above problems, Hu Wenping, researcher of the Institute of chemistry, Chinese Academy of Sciences, has assembled a new conjugated material system with molecular weight between 1-10kda, which is called mesopolymer This kind of conjugated material system avoids the problems of complex synthesis and low yield of traditional oligomers, and shows strict regular structure and excellent charge transfer performance The key to the preparation of high-performance mesoscopic polymer is to control the growth rate of the main chain of the product and to limit the generation of self coupling and β coupling defects on the main chain Traditional conjugated polymers are prepared by Suzuki or still polymerization, which are difficult to control the growth of the main chain accurately The researchers prepared mesopolymers by direct arylation polymerization (DARP), which can be controlled by ligands Through a large number of screening conditions, the researchers found that adamantane phosphine ligands (ad2pnbu) with large steric hindrance and electron rich can meet the above requirements, and the molecular weight of the reaction products can be controlled within the range of 1-10 kDa Based on the model substrate meso dppbtz, the researchers carried out a detailed analysis of the defect structure of the main chain: the temperature rising nuclear magnetic resonance hydrogen spectrum and matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS) proved that meso dppbtz is a strictly regular alternating structure, and there is no self coupling component; the small molecule reference experiment and DFT calculation results proved that meso dppbtz There is no β defect More importantly, the multi batch synthesis of meso dppbtz shows good repeatability UV-vis and UPS show that meso dppbtz has a wider band gap and a deeper LUMO energy level than the corresponding polymer poly dppbtz It is a potential electron and bipolar transport semiconductor material Furthermore, a series of mesoscopic polymers based on different structural units were synthesized by DARP polymerization and their properties were characterized In the device evaluation of the flexible top gate FET, the researchers found that the electronic transmission capacity of the mesoscopic polymer is much higher than that of the traditional polymer (the maximum performance improvement ratio is 124 times) Due to its moderate molecular weight, solubility and viscosity, mesoscopic polymers have shown potential applications in large area solvable devices For example, the performance of FET devices based on the ink-jet printing method is one of the best reported performance As a new type of conjugated semiconductor, mesoscopic polymer is expected to overcome the shortcomings of traditional conjugated materials and achieve a breakthrough in function The new concept material of mesoscopic polymer will further enrich the connotation of organic material system and promote the research of organic photonics, biosensor, biological detection and other related fields This work was recently published in nature Chemistry (DOI: 10.1038 / s41557-018-0200-y).