http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Band gap sensitivity of bromine adsorption at carbon nanotubes
Park, Noejung,Miyamoto, Yoshiyuki,Lee, Kyuho,Ih Choi, Wooni,Ihm, Jisoon,Yu, Jaejun,Han, Seungwu Elsevier 2005 Chemical physics letters Vol.403 No.1
<P><B>Abstract</B></P><P>We report results of our first-principles investigation on the energetics and electronic structures of bromine-adsorbed carbon nanotubes. While the bromine molecule binds preferentially to the outer wall of metallic nanotubes, the binding energy of adsorbed atomic bromines are found to depend on the radius as well as the energy gap. A recent experiment on the nanotube separation using bromines is discussed based on our computational data. The formation of strong C–Br chemical bonds at the zigzag edge of graphite demonstrates a close relationship between the density of states at the Fermi level and the binding strength.</P>
Dongchul Sung,Noejung Park 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.3
We perform {\it ab initio} electronic structure calculations for the metal-carbon nanotube (CNT) interfaces with encapsulated fullerenes (C$_{82}$) or metallofullerenes (La@C$_{82}$). Gold and aluminum layers are chosen as typical examples of metals with a large work function and a small work function, respectively. It is found that the encapsulation of the fullerene species can affect the Schottky barrier height at the metal-CNT interface. We show that the fullerene-derived localized state could weakly pin the metal Fermi level in the gap of the nanotube. We suggest that the transport properties of the metallofullerene-encapsulated CNT should be explained in terms of the Schottky barrier adjustment rather than the band gap reduction model whose validity has been debated in recent publications.
First-principles study of shift current mechanism in various inversion-broken systems
Bumseop Kim,Noejung Park,Jeongwoo Kim 한국자기학회 2021 한국자기학회 학술연구발표회 논문개요집 Vol.31 No.2
Bulk photovoltaic effect characterized by the generation of a steady photocurrent without the aid of external p-n junction has attracted a lot of attention due to its novel physics and potential for high-performance solar cell device. We briefly introduce basic theory of bulk photovoltaic effect and show the electronic origin and photocurrent mechanism in organic molecular solids (TTF-CA), hybrid halide perovskite (MAPbI3 and FAPbI3), and transition metal dichalcogenides (TMDs). For TTF-CA, we show the electronic origin of the photovoltaic property of TTF-CA at low temperature (< 81 K). In the high-temperature phase, despite a net zero current, a non-vanishing shift current can be generated by the interchain effect. In addition, we find that the ferroelectric polarization of the hybrid halide perovskite is largely dominated by the ionic contribution of the molecular cation. In contrast, the photovoltaic nature is mostly determined by the intrinsic electronic band properties near the Fermi level, originating from iodine to lead atoms (inorganic backbone). At last, we investigate the underlying physics of the large bulk photovoltaic effect of the one-dimensional WS₂ nanotube and present the possibility of giant shift current over four times larger than the experimental value in the near-infrared region. Our results provide a fundamental understanding of intriguing bulk photovoltaic materials and pave a way for their practical applications.