Syntheses and characterizations of unconventional azaarenes with nonlinear shapes and novel functional groups

• Main Author: Zhao, Kexiang
• Other Authors: Zhang Qichun
• Format: Thesis-Doctor of Philosophy
• Language: English
• Published: Nanyang Technological University 2020
• Subjects: Engineering::Materials::Organic/Polymer electronics; Science::Chemistry::Organic chemistry::Heterocyclic compounds
• Online Access: https://hdl.handle.net/10356/136769
• Institution: Nanyang Technological University

This thesis aims to address the lack of azaarenes with nonlinear backbone and novel functional groups. Further study on the electronic and optical properties was conducted in order to grasp the structure-property relationship of unconventional azaarenes. Star-shape and U-shape were selected as the nonlinear backbones. Imide and thiadiazole were chosen as the functional groups. In the first result, thiadiazole-fused star-shaped azaarene was synthesized and characterized by NMR, HRMS, UV-Vis and cyclic voltammetry. It was applied in the Perovskite solar cells as electron-transporting material with electron mobility up to 1.73 × 10-2 cm2V-1s-1. A high power conversion efficiency of 18.1% is achieved, which is fully comparable with the efficiency from the control device fabricated with PC61BM as ETL. In the second result, a series of U-shaped helical azaarenes were synthesized and characterized by NMR, HRMS, UV-Vis and cyclic voltammetry. Crystal structures of helical azaarenes were obtained, and the solid-state structures unequivocally exhibited the helicity. Its electronic and optical properties were measured and compared with that of Z-shaped azaarenes. In the third result, a series of novel imide-fused diazatetracenes were synthesized via Buchwald-Hartwig C-N coupling with a highly active palladium source. The obtained diazatetracenes were characterized by NMR, HRMS, UV-Vis and cyclic voltammetry. Its electronic and optical properties were measured and compared with that of unsubstituted diazatetracene. By changing the alkyl chains of the new diazatetracenes, different solid-state packings were achieved. In conclusion, unconventional azaarenes with nonlinear backbone and novel functional groups were successfully acquired. Along with the syntheses, electronic and optical properties were also investigated. Moreover, from all the successful and failed attempts new strategies for more unconventional azaarenes were discovered.