Presentation Information
[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)
Keywords:
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.