Fine-tuned designs of next generation materials for solar photovoltaics

Project Gist

Harvesting “more light!” for photovoltaics

Keywords

Solar cell, Light harvesting, Transparent conducting oxide (TCO), Quantum dot, Organic-inorganic hybrid

Background, Purpose, and Project Achievements

There are two methods to enhance the power conversion efficiency (PCE) of the solar cell. One is harvesting the light to strengthen the irradiation intensity. Another is adjusting the absorption-wavelength-region of the semiconductor to the full-spectral profile of the solar light. Once harvesting the light, the photocurrent density will increase followed by the increment of the photo-induced electromotive force, and finally the enhancement of the PCE will be observed. In this work, we prepared nano-structured indium tin oxide (ITO) electrode with a periodic arrays of holes. We applied it for hybrid organic-inorganic hybrid solar cells and found that the nano-structured ITO led to light scattering and trapping effects. These effects brought the increase of the light concentration in the active layer and thus the increase of the absorption and the enhancement of the PCE. On the other hand, quantum dots of Ag-In-Zn-S system for hybrid organic-inorganic solar cells were prepared and it was found that varying the Zn ratio is enable to change the bandgaps and it is adjustable for that of the conducting polymers in order to enhance the PCE.

Future Prospects

Various patterning and sizes of the periodicity of the nano-structured ITO will be investigated in terms of the influence on the photovoltaic performance of the organic-inorganic hybrid solar cell. While, further extension of the systematic preparation of the quantum dots of Ag-In-Zn-S and the matching of them to the above ITO will be done.

Figures

Photo of glass-ITO/ZnO/conducting polymer poly(3-hexylthiophene) (P3HT)/Ag hybrid solar cell
Photo of glass-ITO/ZnO/conducting polymer poly(3-hexylthiophene) (P3HT)/Ag hybrid solar cell

Principal Investigator

SAGAWA Takashi

・SAGAWA Takashi
・Graduate School of Energy Science
・ He was born in 1965 at Kumamoto and got his degree of Dr. Eng. at Kumamoto Univ. in 1995. His professional experiences were as follows: Assist. Prof. of Kumamoto Univ. since Apr 1990, Assist. Prof. of Kyoto Univ. since Apr 2000, and Assoc. Prof. of Kyoto Univ. since Nov 2006. Thereafter, now he is Prof. of the Graduate School of Energy Science, Kyoto Univ. since Dec 2012. Mission and purpose of his current research are the design of organic and/or inorganic materials and the evaluation of their functions for utilization of photoenergy.
http://www.quantenepro.energy.kyoto-u.ac.jp/