The Effect of Degradation on the Active Layer in APFO3: PCBM Solar Cells

AbstractWe have measured the effect of degradation on the I-V characteristics in APFO3:PCBM solar cells. The solar cell devices were subject to ambient air under simulated solar illumination. We found that the degradation resulted in a lowering of the fill factor and short circuit current while the open circuit voltage remained unchanged. In order to gain insight into what has caused the degraded I-V characteristics we have studied the active layer film using various techniques. We found clear spectral changes both in absorption and in photoinduced absorption spectroscopy correlated with increased carrier lifetimes and lowered mobility when comparing the degraded film with a pristine one. The results show a significant degradation of the active layer causing a lower fill-factor and short circuit current

Comparative Indoor and Outdoor Degradation of Organic Photovoltaic Cells via Inter-laboratory Collaboration

We report on the degradation of organic photovoltaic (OPV) cells in both indoor and outdoor environments. Eight different research groups contributed state of the art OPV cells to be studied at Pomona College. Power conversion efficiency and fill factor were determined from IV curves collected at regular intervals over six to eight months. Similarly prepared devices were measured indoors, outdoors, and after dark storage. Device architectures are compared. Cells kept indoors performed better than outdoors due to the lack of temperature and humidity extremes. Encapsulated cells performed better due to the minimal oxidation. Some devices showed steady aging but many failed catastrophically due to corrosion of electrodes not active device layers. Degradation of cells kept in dark storage was minimal over periods up to one year

The physical meaning of charge extraction by linearly increasing voltage transients from organic solar cells

Carrier mobility in organic solar cells is almost exclusively determined with the Charge Extraction by Linearly Increasing Voltage (CELIV) technique; indeed much of our understanding of the recombination and charge transport mechanisms in organic solar cells is based on CELIV measurements. However, since the conception of the CELIV method, our understanding of organic semiconductors has significantly advanced. In this work, we critically examine the CELIV methods ability to provide accurate material data in the light of recent advances in our understanding of trap states and their influence on mobility in organic semiconductors. We then apply this knowledge to understand the mechanisms responsible for degradation in organic solar cells

ITO‐Free Organic Photovoltaic Modules Based on Fluorinated Polymers Deposited from Non‐Halogenated Solution: A Major Step Toward Large‐Scale Module Production

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