Organic solar cell degradation probed by the nanosecond photoresponse

Abstract

We measure the transient electrical response of small organic solar cells illuminated with nanosecond light pulses during degradation. Our data show the buildup of a significant memory effect in the pulse response. To measure this memory effect, a sequence of positive or negative bias voltages is applied and the pulse response is then recorded at 0-V bias voltage. For devices with a measurable memory effect, this pulse response depends on the previously applied positive or negative bias voltage. The memory effect is attributed to changes in the (3,4-ethylenedioxythiophene):poly (4-styrenesulfonate) (PEDOT:PSS) layer in conjunction with humidity and the indium tin oxide (ITO) layer. The strength of the memory effect depends on the anode material used and the time exposed to humid atmosphere. Therefore, the strength of this memory effect is a measure for the corresponding degradation process.