Spatially resolved photocurrent measurements of organic solar cells: Tracking water ingress at edges and pinholes

Feron, Krishna; Nagle, Timothy J.; Rozanski, Lynn J.; Gong, Bill; Fell, Christopher J.

doi:10.1016/j.solmat.2012.10.027

Cited by 58 publications

(57 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The oxidized organic/electrode interface hinders charge carrier extraction and can be observed as a loss in J sc . This mechanism was confi rmed recently by a study of Feron et al [ 17 ] who used laser beam induced current (LBIC) to spatially resolve the degradation process caused by water ingress either through pinholes or device edges.In order to show that the water-related degradation is strongly promoted by the PEDOT:PSS layer we replaced this layer with other nonhygroscopic hole transport materials based on solution-processed metal-oxides. Furthermore we investigated the stability of the unencapsulated devices under different stress conditions.…”

mentioning

confidence: 77%

“…We suggest that under the accelerated aging conditions the rate of degradation is only governed by the lateral diffusion of water from the edges and through pinholes in the aluminum into the center of the device. [ 17,[35][36][37][38] When a certain water concentration is reached, it will locally lead to a total failure. The insulating interface forms nearly instantaneously.…”

Section: Modelmentioning

confidence: 99%

See 1 more Smart Citation

An Effective Area Approach to Model Lateral Degradation in Organic Solar Cells

Züfle

Neukom

Altazin

et al. 2015

Advanced Energy Materials

View full text Add to dashboard Cite

tooxidation of the poly mer, giving rise to absorption loss and to oxygen doping. [9][10][11] Water ingress can also strongly affect the electrodes and lead to their oxidation or to other chemical reactions. [12][13][14] In solar cells with classical geo metry, degradation often takes place at the organic/cathode interface, [ 15 ] where it has been shown that low-workfunction metals are most susceptible to oxidation. This degradation process can be prevented effectively by either using an inverted geometry [ 16 ] or by replacing the hygroscopic poly(3,4-ethylenedioxythiophene):polysty rene sulfonate (PEDOT:PSS) with alternative hole transport materials (HTM).In a recent study Voroshazi et al. [ 12 ] investigated the process of cathode oxidation in more detail and revealed an important interaction between the lowworkfunction cathode and the widely used PEDOT:PSS hole transport layer (HTL). It was observed that the hygroscopic nature of PEDOT:PSS causes a water ingress from the edges of the device toward the central part and therefore accelerates the oxidation of the Al cathode signifi cantly. The oxidized organic/electrode interface hinders charge carrier extraction and can be observed as a loss in J sc . This mechanism was confi rmed recently by a study of Feron et al. [ 17 ] who used laser beam induced current (LBIC) to spatially resolve the degradation process caused by water ingress either through pinholes or device edges.In order to show that the water-related degradation is strongly promoted by the PEDOT:PSS layer we replaced this layer with other nonhygroscopic hole transport materials based on solution-processed metal-oxides. Furthermore we investigated the stability of the unencapsulated devices under different stress conditions.In order to assess the physical process of degradation in these devices, we investigated them with a multitude of electrical steady-state, transient and impedance characterization techniques, and also employed drift-diffusion modeling with Setfos for deeper insights into the cell operation. [ 24,52 ] The combination of techniques not only allows for a more reliable parameter extraction, [ 18 ] but also helps to identify the governing physical processes by their specifi c signatures in the various techniques. Thus, even by restricting to nondestructive optoelectrical techniques, the degradation mechanisms can be monitored, as will be shown below.In standard unencapsulated poly(3-hexylthiophene):[6,6]-phenyl C61-butyric acid methyl ester solar cells exposed to humid air, the oxidation of the aluminum cathode is known to be a key degradation mechanism. Water that enters the device at the edges and through pinholes diffuses to the organicelectrode interface. The forming oxide acts as a thin insulating layer that gives rise to an injection/extraction barrier and leads to a loss in the device current. In order to understand this behavior in detail various steady-state, transient, and impedance measurement techniques are performed in combination with drift-diffusion simulations. With thi...

show abstract

mentioning

confidence: 77%

Section: Modelmentioning

confidence: 99%

An Effective Area Approach to Model Lateral Degradation in Organic Solar Cells

Züfle

Neukom

Altazin

et al. 2015

Advanced Energy Materials

View full text Add to dashboard Cite

show abstract

“…As presented in Fig. 4a and b 47 It is therefore reasonable to expect a major contribution to water vapor ingress from the hole-extraction layer. Indeed, Fig.…”

mentioning

confidence: 73%

Extending the environmental lifetime of unpackaged perovskite solar cells through interfacial design

et al. 2016

View full text Add to dashboard Cite

show abstract

“…Fortunately, our OPV cells were suffi ciently stable to be able to endure the investigation in ambient atmosphere. This is not always the case for OPV as demonstrated by Feron et al [ 17 ] who used this extreme time demand to their advantage. They noticed that the working area of their solar cells decreased from the outside towards the middle in a linear fashion to create a trapezoidal image.…”

Section: Doi: 101002/adom201400016mentioning

confidence: 99%

2D Characterization of OPV from Single and Tandem Cells to Fully Roll‐to‐Roll Processed Modules with and without Electrical Contact

Krebs

Jørgensen

2014

Advanced Optical Materials

View full text Add to dashboard Cite

A new type of light beam‐induced current 2D mapping system is developed that speeds up acquisition time from hours and days to minutes or even seconds. It is particularly relevant as a tool to characterize printed, large‐scale, organic photovoltaics. Defects inherent to the multi‐layer printing or degradation effects that develop later can be detected with a spatial resolution of <100 μm. It can be used as an in‐line characterization element in the roll‐to‐roll production of organic photovolatics. Several types of electrical connection schemes are developed, including methods suited for continuous web transport. One particularly exciting development is contactless connection through capacitive coupling, which is especially suited for fast roll‐to‐roll characterization of organic photovoltaic modules during the process where electrodes might not be accessible for making a physical electrical contact. Another variation of the technique allows for the extraction of solar cell parameters such as the capacitive time constant, capacitance, and shunt‐ and series resistance at every position (pixel) in the device, which allows new types of 2D mapping that bring out variations and defects in solar cells that are complementary to standard LBIC. It for instance becomes possible to distinguish a short from an open circuit.

show abstract

Spatially resolved photocurrent measurements of organic solar cells: Tracking water ingress at edges and pinholes

Cited by 58 publications

References 32 publications

An Effective Area Approach to Model Lateral Degradation in Organic Solar Cells

An Effective Area Approach to Model Lateral Degradation in Organic Solar Cells

Extending the environmental lifetime of unpackaged perovskite solar cells through interfacial design

2D Characterization of OPV from Single and Tandem Cells to Fully Roll‐to‐Roll Processed Modules with and without Electrical Contact

Contact Info

Product

Resources

About