Related Experiment Video
Updated: Sep 19, 2025

An Electrochemical Cholesteric Liquid Crystalline Device for Quick and Low-Voltage Color Modulation
Published on: February 27, 2019
Modulating Optoelectronic Performance Through Strategic Chlorine Substitution in Diketopyrrolopyrrole-Based
Shifan Wang1, Chen Pan2, Wenju Li2
1School of Material and Chemistry Engineering, Xuzhou University of Technology, Xuzhou 221018, China.
None:
Chlorinated conjugated polymers offer a comparable and cost-effective alternative to fluorinated counterparts in organic electronics, yet a versatile and strategic regulation and optimization approach of their organic field-effect transistors (OFETs) performance remains underexplored. Herein, we report the rational design and synthesis of three chlorinated diketopyrrolopyrrole (DPP)-based copolymers (PDPP-TBT, PDPP-TBTCl, and PDPP-TBTCl2), and reveal the relationship between the molecular structure and OFETs performance. It was found that the reduction of chlorine in PDPP-TBTCl delivers attenuated hole mobilities of 0.011 cm2 V-1 s-1 compared to that of PDPP-TBTCl2 (0.003 cm2 V-1 s-1). Computational investigations uncover that chlorine incorporation induces backbone distortion (from 0-42°), resulting in steric hindrance from chlorine atoms that disrupts polymer planarity reduces the highest occupied molecular orbital (HOMO) energy level (-5.49 eV for PDPP-TBTCl), and enhances thermal stability. This work provides critical insights into balancing electronic modulation and structural integrity in chlorinated conjugated polymers, paving the way for designing high-performance organic semiconductors through halogen engineering.
Related Concept Videos
Photochemical Electrocyclic Reactions: Stereochemistry
Selection Rules: Photochemical Activation
Thermal and Photochemical Electrocyclic Reactions: Overview
Halogenation of Alkenes
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.
ortho–para-Directing Activators: –CH3, –OH, –⁠NH2, –OCH3
ortho–para-Directing Deactivators: Halogens
Polymer Classification: Stereospecificity

