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4단계 BK21사업 화학공학혁신리더 교육연구단에서는 아래와 같이 초청 세미나를 개최하고자 하오니,

관심 있는 대학원생과 연구원들의 많은 참석 바랍니다.

Dear All,

You are cordially invited to a seminar by Dr. Sang-Kyu Park (KIST)

제 목 (Title): Ultraflexible and Stimuli-Responsive Organic Shape Memory Semiconductor Crystals

연 사 (Speaker): Dr. Sang-Kyu Park

- Materials Science and Engineering,

- KIST

일 시: 2021년 6월 21일 (월) 4:00pm

(Date & Time) Monday, June 21st, 4:00pm, 2021

장 소: RIST 3동 3326호

(Venue) Room 3326, 3rd Laboratory Building, RIST

초청교수: 화학공학과 정대성 교수 (Tel. 279-2268)

(Inquiry) Prof. Dae-Sung Chung (Tel. 279-2268)

Abstract:

One of bright futures of organic electronics is in communication with human body. The device must be wearable/implantable on dynamic surfaces such as skin or organs to achieve close human-to-device communication at the interface. Therefore, the device must be mechanically compliant, flexible, or stretchable. Such background is the driving force behind the implementation of flexible/stretchable electronics utilizing organic materials that are considered to be flexible in nature.

Among the most successful examples of stretchable electronic devices are achieved by the geometric engineering (i.e., wavy/ serpentine patterns or kirigami) of hard materials (e.g., silicon, GaAs). Three-dimensional structures are capable of 30–100% stretching within the principle strain below 2%, facilitated by three-dimensional motions. However, the geometric approach requires complicate patterning and transfer printing steps, thus making high-throughput device fabrication difficult. Polymer electronics, on the other hand, utilize inherently stretchable semiconducting polymer or elastomer-polymer blend, which is amenable to large-scale, low-cost solution processing. However, inherently stretchable semiconductor layers are attained at the expense of crystallinity and/or conjugation length, thus it is not a desirable strategy to fulfill disorder-free charge transport and flexibility at the same time.

In this respect, we suggest a new strategy to realize high-performance stretchable electronics. By harnessing a molecular semiconductor crystal that is capable of mechanically-induced martensitic transitions (i.e., reversible, cooperative structural transitions that preserve structural integrity), we demonstrated flexible single-crystal electronic device for the first time. The device exhibited strain tolerance more than 13% while maintaining the charge carrier mobility of unstrained crystals (mobility, μ>0.7 μ0). Furthermore, we expand our work to diversify the martensitic semiconducting materials, establish structure-mechanical property correlation, and reveal molecular mechanism of such intriguing mechanical property, in addition to demonstration of ultra-stretchable single-crystalline thin-film electronics.

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