Overarching goal:

Our research focuses on exploring unconventional approaches that integrate synthesis, self-assembly, fluid dynamics, and scalable processing of nano-materials from both organic and inorganic worlds with complementary strengths, well-defined conformation, morphology, composition and electronic properties for energy harvesting and storage applications. The convergence of these interdisciplinary studies provides revealing insights into the development of new generations of hybrid materials with unprecedented materials properties, especially those pertinent to energy harvesting and storage applications. 

1. Wafer-scale Synthesis of Single Crystalline non-Silicon Materials with Ultrahigh Mobility

The holy grail of next generation electronics is to identify viable alternatives for non-Silicon electronics with synthetic scalability, industry compatible processability, crystallinity, and most importantly, ultra-high mobility. Chemical vapor deposition (CVD) provides an enabling platform to stitch dissimilar atoms into functional molecules where the periodic and repeated arrangement of lattices is perfect and extend throughout the entirely of specimen without interruption, wafer-scale processability, and tunable electronic properties. Current projects straddle across (a) lattice orientations; (b) heterogeneous junctions; (c) dopants; (d) metal contacts; and (e) device integration, respectively. Notable applications include internet of things (IoT), flexible electronics, and next generation semiconductors.

Team: Dr. Hill Chiu, Dr. Hao-Ling Tang, Dr. Liang Cai, Areej Aljarb, Stanley Fu, Yi Wan, Chien-Chih Tseng and Chih-Wen Yang

Collaboration: Prof. Jeehwan Kim and Jing Kong at MIT ; Director Lance Li at TSMC; Prof. Kuo-Wei (Andy) Huang and Prof. Yu Han at KAUST.

2. Printable Transition Metal Dichalcogenides Metamaterials

The deployment of dimensional transitions is ubiquitous in nature, ranging from the Venus flytrap, beating of a heart, sounds shaped by the vocal folds and zooming of focal length by the human eye. External stimuli in the form of chemical or mechanical cues arising from the environment result in the deformation of materials. Such a dimensional transition leads to new functionalities, which cannot be found in their original formats. We explore nature-inspiring synthetic strategies to systematically study the self-assembling behaviors, underlying mechanisms and the associated material properties, ultimately enabling the microscopic integration and macroscopic deployment of these 2D transition metal dichalcogenides into metamaterials. Potential applications include structural reinforcement, energy storage, electrochemical catalysis, responsive smart materials, and sensors.

Team: Dr. Yuanlong Shao, Dr. Yichen Cai, Xuan Wei, Christine Wu, and Ruofan Sun

Collaboration: Dr. Stanley S Chou at Sandia National Lab, USA; Director Yi Liu at the Molecular Foundry Division, Lawrence Berkeley National Lab, USA; Prof. Jing Kong at MIT.

3. High Throughput additive manufacturing of Printable Hybrid Photovoltaics

Organic-inorganic perovskites that combine the strength of both chemical worlds have emerged as tantalizing candidates for next generation photovoltaics. Two of the most formidable challenges are the formation of pin-hole free precursor thin films and the subsequent transformation into highly crystallized absorber upon thermal annealing. To surmount this hurdle, we explore the electrohydrodynamically-assisted continuous liquid interface propagation (clip) as a general, and potentially scalable nanomanufacturing route toward synthesizing high quality perovskite thin films in a rapid and high throughput fashion. This strategy conceptually mimics the advantageous self-organizing features of emulsion droplets where the use of a binary solvent system, concurrently and continuously, initiates a three-stage process of coalescence, spreading, and merging, thus optimizing thin film morphology upon deposition without the needs for additional engineering steps. The resulting perovskite thin film not only exhibits a smooth topology with the root mean square roughness of only a few nm, but also reveals hybrid morphology where micron-sized grains intersperse between interconnected, and continuous crystalline networks. This gives rise to the highest power conversion efficiency of 20.50 % and average 18.68%, representing a nearly two-fold increase compared to that of conventional spray-pyrolysis approach. As a final critical aspect, the proposed strategy contributes new insights to efficiently managing the environmentally hazardous lead during processing, significantly reducing the amount by two orders of magnitude compared to that of spin-coating to achieve the same thin film thickness.

Team: Dr. Liang Cai, Dr. Yuanlong Shao and Oliver Lin

Collaboration: Prof. Thomas Anthopoulos at KAUST; Dr. Stanley S Chou at Sandia National Lab, USA; Prof. Yang Yang at UCLA, USA