Radiation induced damage and recovery in poly(3-hexyl thiophene) based polymer solar cells

Abstract

Polymer solar cells have been characterized during and after x-ray irradiation. The open circuit voltage, dark current and power conversion efficiency show degradation consistent with the generation of defect states in the polymer semiconductor. The polymer solar cell device remained functional with exposure to a considerable dose (500 krad (SiO(2))) and showed clear signs of recovery upon removal of the irradiation source (degraded from 4.1% to 2.2% and recovered to 2.9%). Mobility-relaxation time variation, derived from J-V measurement, clearly demonstrates that radiation induced defect generation mechanisms in the organic semiconductor are active and need to be further studied. Optical transmission results ruled out the possibility of reduced light absorption and/or polymer crystallinity. The results suggest that organic solar cells are sufficiently radiation tolerant to be useful for space applications.

Origin of Radiation‐Induced Degradation in Polymer Solar Cells

“…The polymer solar cells were made using a slow growth approach as described elsewhere. [ 7 ] The device area was 0.12 cm − 2 .…”

“…But before such ideas become a reality and turn to mass production, one important consideration is whether or not such organic cells would be adequately radiation tolerant. We have previously observed [ 7 ] a degradation and recovery phenomenon in PSCs based on a typical material blend of regio-regular poly (3-hexyl thiophene) (RR-P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). We investigate here in detail the effect of radiation on degradation of PSCs and demonstrate that charge accumulation at the interface is the prominent degradation reason for such devices as a result of X-ray radiation.…”

Origin of Radiation Induced Damage in Organic P3HT:PCBM Based Photocells

“…The photocells used in the experiments to be described were identical to those outlined in our earlier publication [4]. They 0018-9499/$26.00 © 2010 IEEE were formed in a layer structure and sandwiched between a glass substrate and a thin, glass cover slide as shown schematically in Fig.…”

“…To complete measurements reported previously [4] we biased cells optically at three different starting values: 0.34 V, 0.40 V and 0.44 V and then irradiated them out to accumulated X-ray doses of 300 krad . was measured at each dose point.…”

“…In a previous publication [4] we began a study of organic photocells based upon a blend of p-type poly 3-hexyl thiophene (P3HT) and n-type [6,6]-phenyl-C61-butyric acid methylester (PCBM) (1:1 by weight ratio). X-irradiation was observed to degrade almost all the critical photo-cell parameters (open circuit voltage, , short-circuit current, , power conversion efficiency, etc).…”