S-Space College of Engineering/Engineering Practice School (공과대학/대학원) Dept. of Mechanical Aerospace Engineering (기계항공공학부) Theses (Ph.D. / Sc.D._기계항공공학부)
Large-area assembly and restructuring of multiscale multidimensional nanoparticle structures and their application to a solar cell
멀티스케일 다차원 나노입자 구조물 대면적 조립 및 재구조화 이의 태양전지 응용
- 공과대학 기계항공공학부
- Issue Date
- 서울대학교 대학원
- 학위논문 (박사)-- 서울대학교 대학원 : 기계항공공학부, 2015. 2. 최만수.
- In order to utilize unique and superior properties of nanomaterials in various fields including modern sciences and engineering, many researches for developing nanomaterials have been reported. In particular, multifunctional properties of multiscale multidimensional structures have attracted great interests for numerous applications such as photonics, sensors, and electronics. Therefore, fabrication methods of multiscale multidimensional structures have been continuously studied. As part of the effort, ion assisted aerosol lithography (IAAL) was introduced as a new technique for multiscale multidimensional assembly of nanoparticles. However, to extend applicability of multiscal multidimensional nanoparticle structures (NPSs) via IAAL showing superior properties, researches for large-area patterning and stiffness increase of NPSs are required. With this motivation, in this study, fundamental techniques to develop IAAL were suggested, and their feasibility was verified by realizing a new-concept nanodevice.
A new technique for large-area assembly of multiscale multidimensional NPSs was proposed by combining IAAL and a multi-spark discharge method. And, three-dimensional (3D) NPSs were uniformly constructed via IAAL utilizing a newly designed multi-pin spark discharge generator over a large area of 50 mm x 50 mm in a parallel manner. The effect of particle sizes on morphologies of NPSs was also studied. In addition, we produced 3D back reflectors based on various 3D NPSs showing superior performance relative to back reflectors fabricated by conventional fabrication methods.
A study on stiffness increase of NPSs via an electron-beam (e-beam) sintering method was performed as another effort to broaden applicability of multiscale multidimensional NPSs. We defined principle of e-beam sintering, and investigated variations in physical properties of NPSs via the e-beam sintering process. Furthermore, a newly combined approach of IAAL and the e-beam sintering technique was developed to fabricate NPSs with unique morphologies.
Based on those fundamental techniques developed herein, we demonstrated a thin-film silicon (Si) solar cell incoporating 3D NPSs with an objective to maximize the light trapping effect. The excellent performance of the thin-film Si solar cell employing 3D NPSs was validated by an experimental comparison with a cell incorporating nanoparticle clusters and by a theoretical comparison with a cell employing nanobump arrays. And, the thin-film Si solar cell with the 3D NPSs showed a 30% increase in short-circuit current density and a 20% increase in efficiency relative to a flat cell.