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세미나 [04/26] Synthesis of Low Dimensional Micro- and Nano-structures for Solar Energy Harvesting Scheme toward Low-Temperature Growth of Two-Dimensional Layered Materials and their device applications 2017.04.21 326

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개최일시 : 2017 04 26일 수요일11:00 ~ 12:00

개최장소 : 4공학관 D406

세미나 제목 : Synthesis of Low Dimensional Micro- and Nano-structures for Solar Energy Harvesting Scheme toward Low-Temperature Growth of Two-Dimensional Layered Materials and their device applications

발표초록 :

In first part of my talk, I will introduce the development of low dimensional nanomaterials in my lab and its applications on Cu(In, Ga)Se2 solar cell. The direct formation of large area Cu(In,Ga)Se2 nanotip arrays (CIGS NTRs) by using one step Ar+ milling process without template. By controlling milling time and incident angles, the length of CIGS NTRs with adjustable tilting orientations can be precisely controlled. Formation criteria of these CIGS NTRs have been discussed in terms of surface curvature, multiple components, and crystal quality, resulting in a highly anisotropic milling effect. In addition to physical approach to form nanostructures on the CIGS film, a reactive mold-assisted chemical etching (MACE) process through an easy-to-make agarose stamp soaked in bromine methanol etchant to rapidly imprint larger area micro- and nano- arrays on CIGS substrates was demonstrated in my group. Interestingly, by using the agarose stamp during the MACE process with and without additive containing oil and triton, CIGS microdome and microhole arrays can be formed on the CIGS substrate. Final part of my talk, i will introduce Au NPs to achieve efficiency enhancement of CIGS flexible photovoltaic devices. The incorporation of Au NPs can eliminate the obstacles in the way of developing ink-printing CIGS flexible TFPV, such as the poor absorption at wavelengths in high intensity region of solar spectrum, and that occurs at large incident angle of solar irradiation. The enhancement of external quantum efficiency and photocurrent have been systematically analyzed via the calculated distributions of electric field. These results suggest a promising way for rapidly improving the performance of CIGS flexible photovoltaic devices with low-cost.

   It is well known that novel condensed matter systems can be understood as new compositions of elements or old materials in new forms. 2D layered materials, including graphene, transition metal dichalcogenides (TMDs) allow the scaling down to atomically thin thicknesses and possess unique physical properties under dimensionality confinement. Chemical vapor deposition (CVD) process is the most popular approach for all kind of 2D materials due to its high yield and quality. Nevertheless, the need for high temperature and the relatively long process time within each cycle hinders for commercial development in terms of production cost. However, the transfer procedure has become one of the major limitations of the overall performance. In the second part of my talk, I will present several approaches, including ultra-fast microwave heating, plasma selective reaction, controlled segregation process by laser irradiation and metal vapers-assisted growth processes developed in my lab to directly grow graphene with controllable thicknesses on arbitrary substrates without any extra transfer process these years. In addition, I will also introduce the development of various methods, including laser irradiation assisted-selenization (LIAS) process, fast microwave annealing and plasms enhance selenization processes on different two-dimensional transition metal dichalcogenides (TMDCs) materials in my lab. The device applications based on graphene and TMDCs will be also demonstrated.

 

강연자 : Yu-Lun Chueh, Professor / Department of Materials Science and Engineering, National Tsing-Hua University

초청자 : 전기전자공학과 교수 안종현

 

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