Origin of Radiation‐Induced Degradation in Polymer Solar Cells

Kumar, Ankit; Devine, R. A. B.; Mayberry, Clay; Li, Gang; Yang, Yang

doi:10.1002/adfm.201000374

Cited by 78 publications

(79 citation statements)

References 29 publications

(19 reference statements)

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“…Degradation in OPVs can primarily occur in three places: 1) in the bulk of the active polymer/organic layers; 2) at the interface of the polymer and the electrode; [ 9,10 ] and 3) at the electrode itself. In this paper, we focus on degradation of the bulk photoactive layer under solar illumination.…”

Section: Introductionmentioning

confidence: 99%

The Critical Role of Processing and Morphology in Determining Degradation Rates in Polymer Solar Cells

Kumar¹,

Hong²,

Sista³

et al. 2010

Advanced Energy Materials

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With rapid increase in the efficiencies of polymer solar cells (PSCs) in the last few years, the issue of device stability is taking center stage in organic photovoltaic research. In this work, the effects of oxygen and light on the degradation of charge‐transport properties of the bulk polymer active layer are studied over short timescales. It is shown that although different processing techniques produce similar efficiencies for pristine devices, they result in different degradation rates. This variation in degradation rates is primarily due to slightly different morphology parameters, such as molecular packing or disorder in the film. Investigation reveals that the choice of processing for the devices should consider degradation rates as a critical parameter, not just the efficiencies of the pristine devices. It was found that degradation starts with broadening of the effective density of states due to photo‐oxidation. Both transient absorption and charge extraction by linearly increasing voltage (CELIV) measurements show increase in disorder in the films with progressive degradation. It is suggested that annealing provides the necessary thermal energy to reduce the trap states by flattening out the energy landscape of the pristine films, improving not only the efficiency, as reported previously, but also slowing the degradation rates.

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Section: Introductionmentioning

confidence: 99%

The Critical Role of Processing and Morphology in Determining Degradation Rates in Polymer Solar Cells

Kumar¹,

Hong²,

Sista³

et al. 2010

Advanced Energy Materials

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“…Although a microscopic model for n in BHJ OPV is missing, it is accepted that the ideality factor reflects the "opening behavior" of the diode with the applied voltage with respect to its recombination behavior. 41 It was also proposed for OPV that n > 2 could be related to the tunneling effect 42 (where recombination is intensified by tunneling of charge carriers) or due to reduced mobility in disordered materials where Einstein relation is generalized and can differ from its classical form with n ¼ 1. 43 Anyway, a change in the ideality factor could be evidence of a different type of mechanism for the recombination losses at the junctions.…”

Section: B Light Intensity Dependence Of V Ocmentioning

confidence: 99%

Origin of size effect on efficiency of organic photovoltaics

Manor

Katz

Tromholt

et al. 2011

Journal of Applied Physics

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It is widely accepted that efficiency of organic solar cells could be limited by their size. However, the published data on this effect are very limited and none of them includes analysis of light intensity dependence of the key cell parameters. We report such analysis for bulk heterojunction solar cells of various sizes and suggest that the origin of both the size and the light intensity effects should include underlying physical mechanisms other than conventional series resistance dissipation. In particular, we conclude that the distributed nature of the ITO resistance and its influence on the voltage dependence of photocurrent and dark current is the key to understanding size limitation of the organic photovoltaics (OPV) efficiency. Practical methods to overcome this limitation as well as the possibility of producing concentrator OPV cells operating under sunlight concentrations higher than 10 suns are discussed.

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“…It suggests that degradation of the active materials in solution does not greatly influence the V oc . The result is different to the normal degradation process of OPV devices that causes interface problems, resulting in a decrease in the built-in potential and V oc (Kumar et al, 2010). For the blend solutions, the J sc exhibits only a small decrease even after two months, while the FF shows a gradual decrease with solution storage time ( Fig.…”

Section: Device Characterization and Analysismentioning

confidence: 74%