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  • Next generation perovskite solar cell with improved the efficiency and stability by utilizing the nickel oxide ultrathin

    Energy Science Prof. SHIN, HYUN JUNG

    Next generation perovskite solar cell with improved the efficiency and stability by utilizing the nickel oxide ultrathin

    Researchers recently have focused on organic-inorganic hybrid perovskite materials that would allow low-cost and highly efficient photovoltaic since the power conversion efficiency (PCE) of this cell has rapidly increased from 2.2 % in 2008 to 22% in 2016. The device architecture is composed of electrodes, perovskite photo-active layer with charge transport layers as an interlayer. Although organic hole transport layers are usually used for hole extraction, it is very vulnerable to heat, light, and moisture. Alternatively, the researchers developed perovskite solar cells using inorganic NiO as HTL grown via atomic layer deposition (ALD). The team synthesized ultra-thin (~ 5 nm) NiO films having high transmittance as well as low series resistance, finally demonstrated stable and efficient perovskite solar cells. Researchers also studied to deposit highly dense electron transport layers (ETL) using ALD on top of perovskite in order to improve the stability of the perovskite solar cells. The highly dense ALD-ETL protects moisture transmission from outside greatly and also suppresses decomposition of perovskite from inside. They demonstrated highly stable perovskite solar cells using ALD-ETL without further encapsulation technique and performance loss. This work was published in the journals; Nanoscale (2016) and Nat. Energy (2016).

  • Generating Metamaterial, Inspired by the Motion Control of an Aphid’s Leg

    SKKU Advanced Institute of Nano Technology Prof. LEE, SEUNGWOO

    Generating Metamaterial, Inspired by the Motion Control of an Aphid’s Leg

    Generating Metamaterial, inspired by the motion control of an Aphid’s leg Metamaterials have made the exotic control of the flow of electromagnetic waves possible, which is difficult to achieve with natural materials. In recent years, the emergence of functional metadevices has shown immense potential for the practical realization of highly efficient photonic devices. However, complex and heterogeneous architectures that enable diverse functionalities of metamaterials and metadevices, have been challenging to realize because of the limited manufacturing capabilities of conventional fabrication methods. In this research, it was discovered that three-dimensional (3D) modular transfer printing can be used to construct diverse metamaterials in complex 3D architectures on universal substrates, which is attractive for achieving on-demand photonic properties. This study is inspired by Dry-adhesion Control of the leg of an Aphid, which climbs walls without sticky materials and moves upside down on plant stems. By Dry-adhesion Control, Aphids can regulate the attractive force between leg and object without any restriction. As described in picture 1, the surface area of the leg that is touching the object can be maximized or minimized, depending on the blood pressure of the back of the leg. In this research, a rubber stamp is designed and made to work in a similar manner with that of this insects’ leg motion. As seen picture 2, the rubber stamp with a sharp end can print anything easily due to a minimized surface area (adhesion-off) between metamaterials and the rubber stamp. Metamaterial can be removed from the maximized surface area (adhesion-on) if the sharp end crumbles. This method provides a fascinating route to generate flexible and stretchable 2D/3D metamaterials and metadevices with heterogeneous material components, complex device architectures, and diverse functionalities. About Research Laboratory of Biomimetic & Photonic Properties The Research Laboratory of Biomimetic & Photonic Properties was established in 2014 as a part of SKKU Advanced Institute of Nanotechnology (SAINT). Prof. SeungWoo Lee and 7 students of undergraduate and graduate levels are researching biomimetic by using ductile nanomaterial such as DNA origami/ polymers to create various light-material interactions and more. The laboratory is pursuing the convergence of various academic knowledges, including chemical engineering, physics, electrical engineering, and chemistry. We participate in the competition of biomimetic design at Harvard University, and several joint researches are in development with MIT, Harvard University, and Caltech. /생체모사+ 연성광학 연구실/ 2014년 성균나노과학기술원에 (성균관대 나노과학기술학과 대학원, SKKU Advanced Institute of Nanotechnology(SAINT))설립, 이승우 교수의 지도로 박사후연구원 1명, 석박통합 3명, 학부연구생 3명이 열심히 연구하고 있다. 생체모사를 또는 DNA 오리가미/고분자와 같은 스마트 연성나노물질을 이용하여 다양한 빛-물질 상호작용들을 혁신하는 연구를 수행 중이다. 특히 꽃잎의 구조색, 사하라 사막의 개미가 열을 식히는 원리를 모사하여 태양전지/LED와 같은 광전자소자 효율을 높이거나, DNA를 이용 알고리즘 자리조립으로 비자연적 극한 광학 물성을 유도하는 “알파고 메타물질”연구를 수행 중이다. (seungwoo.skku.edu) 화학공학/나노바이오/나노화학/물리/재료공학/전자공학의 다양한 학문적 융합을 추구한다. 실제 화학공학, 물리, 전자공학, 화학을 전공한 학생들이 모여서 창의적 융합연구를 수행중이다. Harvard에서 열리는 생체분자디자인 경진대회 참석 및 MIT/Harvard/Caltech 대학교와의 공동연구 등 다양한 국제협력도 진행중이다.

  • Bio-Oil Upgrading: using supercritical fluid to produce electricity and biofuels for next generation

    Mechanical Engineering Prof. KIM, JAEHOON

    Bio-Oil Upgrading: using supercritical fluid to produce electricity and biofuels for next generation

    Among various heat transfer processes for biomass that are not dealing with food resources, “fast pyrolysis” is the most famous one. This process is derived from empty palm fruit bunch, which decomposes the material for a few seconds at the temperature of 400-600°C in an oxygen free environment, which produces liquid bio-oil. However, this process has many weaknesses like; (1) low heat stability and short storage period, (2) low energy content, (3) an instability to combine with fossil fuels, (4) low pH causing corrosion of machines, (5) separation of materials if stored for a long time. Due to these weaknesses, bio-oil is not easy materials to transfer, store, and use. This research is about bio upgrading and eliminating weaknesses they have seen in the original “fast pyrolysis” process. Unlike the typical bio oil upgrading process using the usual catalyst, this research is not using a catalyst or hydrogen. Instead, they use in-situ generated hydrogen and supercritical alcohols to upgrade bio oil. And from this research, the research team was able to find that temperature and heat transfer characteristics are similar to medium grade oil. They believe the upgrade bio-oil from this process will generate green electricity and bio gasoline as well as, bio diesel for automobiles.

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