Organic bioelectronics is the convergence of organic electronics and biology. Motivated by the
unique combination of both electronic and ionic conductivity, organic semiconducting
materials have been applied in OECTs for sensing applications to translate bio-logical signals
into a quantitative electrical reading. Due to their carbon-based structure and flexibility, CPs
can achieve improved biocompatibility compared to inorganic devices as they are intrinsically
“softer”, avoiding mechanical mismatch and the need for surface compatibilizing layers. These
promising materials have broad potential to be used in applications such as biosensors, drug
delivery, and neural interfaces.
In the second chapter, a series of lysine-functionalized DPP3T semiconducting polymers,
outline their synthesis, and demonstrate that these particular polymers allow neuron cells to
adhere and grow, in comparison to unfunctionalized polymers, where cells quickly die.
Through covalent attachment of small lysine units, the conjugated polymer backbone and cells
can directly electrically communicate, favorable for neural signals recording/stimulating.
In the third chapter, NDI-based semiconducting polymers are selected for lysinefunctionalization,
giving protein-like surfaces for neurons to attach, grow and form a network
without the need of an intermediate PDL coating. Most importantly, this careful choice of NDI
backbone allows lysinated-NDI polymers to operate in OECTs with an outstanding normalized
transconductance value of 0.25 S/cm.
In the fourth chapter, a new technique is presented to biofunctionalize thin film surface of
polymers. Two methods including CuAAC and thiol-ene click are demonstrated to be
applicable to biofunctionalize surface. In particular, both of them can achieve biocompatible
surface by attaching biomolecules at high density while maintaining electrically conductive
In the final chapter, three series of NDI-T2 are presented synthesized via Stille coupling
reaction using different Pd catalysts. Following electrochemical and device characterization,
the study of the influence of spacers between backbone and EG chain for performance in OFET
and OECT operations is carried out. It is clearly evidenced that electron mobility increases by
a factor of 10 with gradual increased spacers for all polymers in OFETs devices. For OECTs,
within three series, pNDI-Cx-T2 stands out, especially pNDI-C4-T2 giving the highest reported
transconductance at 0.479 S/cm and a low threshold voltage of 0.18 V.
|Date of Award
- Physical Sciences and Engineering
|Iain Mcculloch (Supervisor)
- Conjugated Polymers
- Semiconducting Polymers