講演情報
[22p-A307-1]Time-resolved photo-assisted Kelvin probe force microscopy on Cu(In,Ga)Se2 solar cells to investigate photon energy dependence of photovoltage
〇Shenwei Li1, Takahashi Takuji1,2 (1.IIS, Univ. of Tokyo, 2.INQUE, Univ, of Tokyo)
キーワード：
Kelvin probe force microscopy、Solar cell、Time-resolved measurement
In a Cu(In,Ga)Se2 [CIGS] solar cell which is very promising as a thin film solar cell, we have already found that generated photovoltage depended on a photon energy of incident light. In this study, we have investigated temporal response of photovoltage of the CIGS solar cell by time-resolved photo-assisted Kelvin probe force microscopy (Tr-PKFM) for further investigation of the photon energy dependence of photovoltage.
Our Tr-PKFM, where an intermittent bias application method in KFM, pump-probe KFM, and photo-assisted KFM are combined, realizes very local measurements of time-resolved photovoltage. We succeeded in observing the surface potential change in time domain as well as the change of photovoltage distribution with 2 usec step. We found that the photovoltage around grain boundary (GB) rapidly increased, being attributable to accumulation of photo-generated electrons near GB owing to downward band bending in the conduction band around GB. Similar experiments were conducted under the light with a different photon energy and on another CIGS solar cell with a different Ga content, whose results will be discussed in the presentation.
Our Tr-PKFM, where an intermittent bias application method in KFM, pump-probe KFM, and photo-assisted KFM are combined, realizes very local measurements of time-resolved photovoltage. We succeeded in observing the surface potential change in time domain as well as the change of photovoltage distribution with 2 usec step. We found that the photovoltage around grain boundary (GB) rapidly increased, being attributable to accumulation of photo-generated electrons near GB owing to downward band bending in the conduction band around GB. Similar experiments were conducted under the light with a different photon energy and on another CIGS solar cell with a different Ga content, whose results will be discussed in the presentation.