Nanoscale observation of organic thin film by atomic force microscopy

• Published in: Japanese Journal of Applied Physics Vol. 56; no. 8S1; pp. 8 - 13
• Main Authors: Mochizuki, Shota, Uruma, Takeshi, Satoh, Nobuo, Saravanan, Shanmugam, Soga, Tetsuo
• Format: Journal Article
• Language: English
• Published: Tokyo The Japan Society of Applied Physics 01-08-2017; Japanese Journal of Applied Physics
• Subjects: Atomic force microscopy; Butyric acid; Contact potentials; Energy distribution; Energy harvesting; Film thickness; Frequency modulation; Microscopy; Nanoparticles; Organic semiconductors; Photoelectricity; Photovoltaic cells; Quantum dots; Semiconductors; Solar cells; Solar energy; Weight reduction; Zinc oxide; Zinc oxides
• ISSN: 0021-4922; 1347-4065
• DOI: 10.7567/JJAP.56.08LB08

Organic photovoltaics (OPVs) fabricated using organic semiconductors and hybrid solar cells (HSCs) based on organic semiconductors/quantum dots (QDs) have been attracting significant attention owing to their potential use in low-cost solar energy-harvesting applications and flexible, light-weight, colorful, large-area devices. In this study, we observed and evaluated the surface of a photoelectric conversion layer (active layer) of the OPVs and HSCs based on phenyl-C61-butyric acid methyl ester (PCBM), poly(3-hexylthiophene) (P3HT), and zinc oxide (ZnO) nanoparticles. The experiment was performed using atomic force microscopy (AFM) combined with a frequency modulation detector (FM detector) and a contact potential difference (CPD) detection circuit. We experimentally confirmed the changes in film thickness and surface potential, as affected by the ZnO nanoparticle concentration. From the experimental results, we confirmed that ZnO nanoparticles possibly affect the structures of PCBM and P3HT. Also, we prepared an energy band diagram on the basis of the observation results, and analyzed the energy distribution inside the active layer.