Polymer Innovation for Advanced Organic Electronics (PI-AOE) at Purdue University


Polymer Innovation for Advanced Organic Electronics and Bioelectronic Medicine​

Our group innovates organic (polymer) semiconductors for advanced electronics and iontronics, and tailor their optical, electronic and mechanical properties for the unmet needs.

Organic Synthesis is the foundation for our polymer innovation. We explore new synthetic approaches to prepare novel conjugated building blocks for making organic semiconductors. For instance, we currently work with the Uyeda's group to stitch N=N bond into molecular and polymeric semiconductors with the newly developed Ni-bimetallic catalysts (shown below). In addition, one of our perpetual fondness is to design electron-deficient building blocks and n-type conjugated polymers. We have recently shown that we can purposely tune the LUMO levels of a conjugated polymers while their HOMO levels remain intact. This efficient synthetic strategy is made possible by discovering the oxidative coupling of two electronic deficient building blocks.  

We are particularly interested in liquefying organic semiconductors - that can be melt at the desired temperature and show fluidic properties. At present, we take advantage of inserting flexible spacers into conjugated backbones and installing asymmetric side chains to modulate melt transitions of polymers. Semiconducting polymers with melt processing temperatures as low as 130 oC have been prepared with a record mobility as high as 1 cm2/Vs. We are still actively looking for other design principles that can lead to liquefy organic semiconductors.   

Chemical and electrochemical doping is our frequently used tool to make new molecules and polymers, and particularly optical materials with near-IR absorption. These highly doped materials find a wide range of applications from interfacial materials to photoacoustic imaging contrast agents.  

Materials Processing and Characterizations are critical components in our research efforts. Our materials are processed into thin films and fibers through spin-coating, spray coating, slot-die coating, microgravure coating, as well as melt-drawing. The optical, electronic and mechanical properties of these thin films and fibers are highly dependent on the processing conditions. To understand our materials, we use a wide array of tools to characterize them, ranging from surface topology by atomic force microscopy and polarized optical microscopy, thin film morphology by powder X-ray diffraction and 2D grazing incidence X-ray diffraction, mechanical properties by nano-indentation and buckling test, as well as their electronic properties by field-effect transistors and conductivity measurements. The essential goal is to establish the relationship of chemical structures-materials processing - thin film morphologies - functional properties (e.g. mechanical, optical and electronic properties).      

Device Fabrication and Integration are indispensable when it comes to demonstrate the potentials of our materials. There are three primary electronic devices we build in the laboratory, including organic field-effect transistors (OEFTs), organic thermoelectrics (OTEs), and organic electrochemical transistors (OECTs)​

OEFTs are the basic building blocks for flexible integrated circuits and displays. To make OFETs, materials ranging from conductors (for electrodes), semiconductors (for active channel materials), to insulators (for gate dielectric layers) are needed. We evaluate the potential of our materials as high-performance p- and n-type organic semiconductors. 

OTEs directly convert thermal energy into electric energy are particularly attractive for low-quality waste heat harvesting. Organic thermoelectrics are still in their initial development stage facing various challenges. One of these challenges are the exploration of organic thermoelectric materials with high ZT value. The second challenge is their unclear operation mechanism. Many physical processes, including charge transport, phonon transport, phonon scattering and their combined effect, are involved in thermoelectric conversion, and lead to a complicated operating mechanism.The S-σ trade-off relationship, σ-κ relationship, and relationship between energy level and S constitute several questions for organic thermoelectric materials. We strive to develop materials with high ZT values and understand the operation mechanisms in order to reconcile the trade-off relationships.

Organic Bio-electronics are a generic platform with unprecedented biological recording and regulation potentials -  a technology that bridges biology with electronics. It is based on a unique combination of both electronic and ionic conductivity presented by conducting and semiconducting polymers that enables a means to effectively interface biology with conventional electronics. In our group, we design and synthesize such electronic and ionic polymers, integrate them into organic electrochemical transistors (OECTs), and use these devices to interrogate interesting biological processes such as neural activities, as well as disease diagnosis and monitoring.

We are part of the MI-BIO team, which is dedicated to design and synthesis of new bioelectronic materials, and accelerating bioelectronic materials discovery and implementation.

Scalable Manufacturing of Organic Electrochromic Materials and Devices

Electrochromic glass is a type of electronic device that can change its light and heat transmission properties, which render energy saving and bring user visual comfort. The major obstacles for current electrochromic technologies to be adopted by the market are 1) premium pricing, ​2) the lag in response time between the colored and the bleached states; and 3) the lack of color neutrality (neutral grey color). In addition, the current electrochromic technologies are incapable of turning millions of existed static windows into dynamic switchable windows. By applying an adhesive layer onto roll-to-roll manufactured thin film electrochromic foils, which can then be laminated onto a flat/curved glass architecture – we investigate an electrochromic technology that is scalable, cost-effective, and fulfills unmet needs in the switchable glass industry. We currently focus on scale-up synthesis of electrochromic polymers and roll-to-roll fabrication of electrochromic devices by partnering with industrial experts.  ​

"In our lives, we're constantly taking risks and changing our lifestyles and discovering new things by trial and error. If you're not making a few mistakes, you're probably not doing very much. Only by taking risks do you make progress"  
​Arnold Beckman

"The desire that guides me in all I do is the desire to harness the forces of nature to the service of mankind."
Nikola Tesla ​

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Ambilight: make glass smart

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