Performance Evaluation Method of Organic Photovoltaics under Indoor Light Condition

Organic photovoltaics are expected to be suitable for indoor use because they have a relatively high conversion efficiency even at a low irradiance when compared to crystalline silicon photovoltaics. However, the performance measurement procedures of such photovoltaics under indoor light have not been established. In this paper, the illuminance fluctuation of a commercially-available light device originating from an AC power source has been precisely investigated, and the methods to decrease the influence of this fluctuation on the J-V measurements of the photovoltaics were proposed. Furthermore, an LED light irradiation apparatus was developed for more reliable and reproducible J-V measurements of the photovoltaics. This apparatus was found to provide an excellent time stability of illuminance and in-plane uniformity, both of which satisfy the Class A solar simulator permitted by IEC 60904-9. J-V characteristics of the photovoltaics determined by using this apparatus was coincident with that determined by using a commercially-available LED light driven by an AC power source. Finally, it was confirmed that the conversion efficiency of a DSC is greater than that of a Si photovoltaic under the indoor light condition, the illuminance of which is several tens to hundreds lx.