163 Xianlin Road, Nanjing, +86 18545625709 | [email protected]

EDUCATION Nanjing University, Nanjing, China 2015–present Bachelor of Engineering, Microelectronic Science and Engineering GPA: 3.6/4.0, rank: 3/47 Research Interests: quantum science; 2D materials; photonics; electromagnetics; nanotechnology;

RESEARCH EXPERIENCE Research Assistant 2016–present National Laboratory of Solid-State Microstructures in China Speed up ferroelectric organic transistor memories using 2D molecular crystalline semiconductors 12/2016-04/2017 • Deposited P(VDF-TrFE) polycrystalline film as the ferroelectric gate insulator. • Obtained 2D C8-BTBT molecular semiconducting crystals and PMMA layer using vertical phase separation effect in a mixture solution. The inserted PMMA buffering layer between the insulator and semiconductor acts to suppress the polarization fluctuation at the interface efficiently. • Characterized the morphology and crystalline properties of 2D C8-BTBT layers via AFM. • Characterized electrical properties of Fe-OFET memories devices. • Conclusions:  Ultrathin 2D molecular crystals with low access resistance and fast charge transport can realize rapid operation speed ~3 ms, high on/off ratio of 106 and large memory window ~12 V.  The PMMA layer is beneficial in reducing P(VDF-TrFE) surface roughness to promote the charge carrier transport at the semiconducting channel.

Directly writing 2D organic semiconducting crystals for high-performance field-effect transistors 04/2017-07/2017 • Deposited 2D molecular crystals via the hand-writing process. • Characterized electrical properties of OFETs exhibiting a record-high carrier mobility of 5.9 cm2V−1s−1. • Investigated effect of anti-solvent and writing speeds on forming continuous and large-area 2D crystals. • Conclusions:  Verified rollerball pen’s potential for achieving 2D molecular crystals because its flow behavior can lead to limited molecular quantity and high evaporation rate at the solution edge and thus generate coffee-ring-driven assembly in this location.  Demonstrated a simple and efficient approach to directly write 2D organic crystals for high-performance, large-area printed electronics.

Millimeter-Sized Two-Dimensional Molecular Crystalline Semiconductors with Precisely Defined Molecular Layers via Interfacial-Interaction-Modulated Self-Assembly 04/2018-10/2018 • Obtained bilayer or monolayer molecules from polycrystalline films in a self-assemble growth by tuning annealing temperature. • Characterized surface energy of C8-BTBT and SiO2 substrates by OWRK method to explain the packing dynamic in the growth process. • Tested the controllability of thermally induced self-assembly and found a large temperature window ~20 ℃ for precisely controlling the molecular layer number into 2L or 1L. • Characterized electrical properties of OFETs with 2L films showing a maximum mobility of 12.8 cm2V−1s−1. • Constructed heterojunctions with the 1L films acting as interfacial molecular templates achieving well-balanced ambipolar transport behavior. • Conclusions:  The van der Waals interaction between C8-BTBT molecules on SiO2 and 1L C8-BTBT substrates are larger than that between C8-BTBT, which leads to more stable states (1L and 2L) than upper molecules and thus determines the interfacial molecular packing into 2D films.  Demonstrated 2D molecular crystalline films with well-defined layer numbers and millimeter-sized coverage and showed its potentials in high-performance and low-cost electronic applications.

Ongoing research 06/2018-present • Investigating vertical injection and transport of carriers in thin-film transistors.

PROFESSIONAL EXPERIENCE Full-time Research Assistant Sept. 2017 National Institute for Materials Science (NIMS) in Japan Supervisor: Professor Kazuhito Tsukagoshi (MANA Principal Investigator/ Group Leader, NIMS) • Wrote well-packed n-type molecular crystals to improve the performance of low-voltage OFETs. • Investigated substrate induction for the microphase formation of solution-processed ultrathin P(VDF-TrFE) films under room temperature; Used Raman and AFM to analyze the phase and morphology properties.

SKILLS Laboratory: glove box, optical microscope, vacuum thermal evaporation system, Raman spectroscopy, probe station, autonomic layer deposition, atomic force microscope, X-ray diffraction Computer: C programming, MATLAB, COMSOL, Adobe Photoshop Languages: Chinese (native), English (fluent); GRE: 330, TOFEL: 105

AWARDS & CERTIFICATES National Scholarship 2018 National Encouragement Scholarship 2016, 2017 People’s Scholarship 2015, 2016 Excellent Student Leader 2016

PUBLICATIONS 1. Yujia , Yu Guo, , Jun , Sai Jiang, Qijing , Xinran Wang, Shi*, Xiaomu Wang * and Yun *, “Directly Writing 2D Organic Semiconducting Crystals for High-Performance Field-Effect Transistors”, Journal of Materials Chemistry C, 2017, 5, 11246-11251 (cover feature)

2. Lei Song ‡, Yu Wang ‡, Qian , Yu Guo,Qijing Wang, Jun Qian, Sai Jiang, Bing , Xinran Wang, Yi Shi*, Youdou , and Yun Li*, “Speed up Ferroelectric Organic Transistor Memories by Using Two-Dimensional Molecular Crystalline Semiconductors”, ACS Applied Materials & Interfaces, 2017, 9(21), 18127-18133

3. Yujia Zhang, Haiyang Wang, Lei Zhang, Xiaomeng , Yu Guo, Huabin , and Yun Li*, “Field-Effect Transistor Memories Based on Ferroelectric Polymers”, Journal of Semiconductors, 2017, 38(11), 111001-14

4. Sai Jiang, Jun Qian, Yiwei , Hengyuan Wang, Jianhang Guo, Yu Guo, Qijing Wang*, Yi Shi, and Yun Li*, “Millimeter-Sized Two-Dimensional Molecular Crystalline Semiconductors with Precisely Defined Molecular Layers via Interfacial-Interaction-Modulated Self-Assembly”, Journal of Physical Chemistry Letters, 2018, 9, 6755-6760

5. Yu Guo, Yi Shi, Introduction to Organic Semiconductor Materials & Flexible Substrate Technology, In Integrated Circuits Industry [M]; China Industrial and Commercial Publishing Group: Beijing, 2018; pp, 1780-1784

PRESENTATIONS 1. Yujia Zhang, Yu Guo, “Directly writing 2D organic semiconducting crystals for high-performance field-effect transistors” International Thin-Film Transistor Conference (ITC 2018), Guangzhou, China, March 2018 (Poster) 2. Yu Guo, “Solution-processed 2D organic molecular crystals”, School of Electronic Science and Engineering, Nanjing University, Nanjing, China

EXTRACURRICULAR ACTIVITIES Grade Leader, School of Electronic Science and Engineering 2015–2016 • Aided fellow students to solve problems in both scholastic activities and daily life

Director of Publicity, Department of Student Union 2016–2017 • Designed event posters, magazine cover and environmental protection slogan with Adobe Photoshop • Established the college’s free media platform

Youth League Secretary, School of Electronic Science and Engineering 2016–2017 • Organized various extracurricular activities