Development of Microscopic Analysis Method of Organic Solar Cells

2018 Fiscal Year Final Research Report

• Project/Area Number: 15H02023
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Thin film/Surface and interfacial physical properties
• Research Institution: University of Tsukuba
• Principal Investigator: Takeuchi Osamu 筑波大学, 数理物質系, 准教授 (20361321)
• Project Period (FY): 2015-04-01 – 2019-03-31
• Keywords: 走査プローブ顕微鏡 / 太陽電池

Outline of Final Research Achievements

A microscopic measurement technique that can visualize the nanometer-scale distribution of local conversion performance in highly non-uniform organic solar cell devices was developed, where a scanning tunneling microscope (STM) is used to locally collect the photocarriers that were generated in an illuminated solar cell. The developed technique, light-modulated STM (LM-STM) allows us to acquire local I-V characteristics of solar cells as well as their illumination intensity dependence. It was pointed out that, compared to the macroscopic device I-V characteristics, the acquired local I-V characteristics are generally much more strongly affected by the inner resistance of the device materials and a guideline how to extract the local carrier generation rate and photovoltage from such local I-V characteristics is given. A new type of pulse-laser-assisted time-resolved STM system was developed to measure the local carrier life time in a solar cell device.

Free Research Field

物理工学

Academic Significance and Societal Importance of the Research Achievements

製造の省力化・省コスト化のため、最新の太陽電池はアモルファスや多結晶のような不均一構造を持つことが多く、デバイス内には高性能な部分と低性能な部分とが混在している。局所性能を測定可能な顕微鏡はそのような複雑なデバイスの動作を理解し、さらなる高効率化を目指すために特に有用である。本研究は光変調トンネル分光法により局所性能を評価可能であることを示しただけでなく、得られる結果をどのように解釈すれば局所性能を決める重要な物理パラメータを取り出せるかという指標を与えるものである。また光キャリア寿命という別のパラメータを計測するための時間分解トンネル顕微鏡の開発も行った。