Mechanical properties of amorphous indium-gallium-zinc oxide thin films on compliant substrates for flexible optoelectronic devices

Amorphous indium–gallium–zinc-oxide (a-IGZO) thin films were deposited using RF magnetron sputtering on polyethylene naphthalate (PEN) and polyethylene terephthalate (PET) flexible substrates and their mechanical flexibility investigated using uniaxial tensile and buckling tests coupled with in situ optical microscopy. The uniaxial fragmentation test demonstrated that the crack onset strain of the IGZO/PEN was ~ 2.9%, which is slightly higher than that of IGZO/PET. Also, uniaxial tensile crack density analysis suggests that the saturated crack spacing of the film is strongly dependent on the mechanical properties of the underlying polymer substrate. Buckling test results suggest that the crack onset strain (equal to ~ 1.2%, of the IGZO/polymer samples flexed in compression to ~ 5.7 mm concave radius of curvature) is higher than that of the samples flexed with the film being in tension (convex bending) regardless whether the substrate is PEN or PET. The saturated crack density of a-IGZO film under the compression buckling mode is smaller than that of the film under the tensile buckling mode. This could be attributed to the fact that the tensile stress encouraged this crack formation originating from surface defects in the coating. It could also be due to the buckling delamination of the thin coating from the substrate at a lower strain than that at which a crack initiates during flexing in compression. These results provide useful information on the mechanical reliability of a-IGZO films for the development of flexible electronics.The authors would like to thank DuPont-Teijin for donating polymer samples. We would also like to thank Mr. Frank Biddlestone for his technical support and Mr. Warren Hay for his help in the workshop. Financial support from the Kurdistan Regional Government HCDP programme is gratefully acknowledged. The atomic force microscope used in this research was obtained, through Birmingham Science City: Innovative Uses for Advanced Materials in the Modern World (West Midlands Centre for Advanced Materials Project 2), with support from Advantage West Midlands (AWM) (DD-07) and partly funded by the European Regional Development Fund (ERDF) (SY/SP80). R.W. gratefully acknowledges funding from the EPSRC Centre for Doctoral Training in Photonic Systems Development.This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.tsf.2015.09.05

Ultrathin and lightweight organic solar cells with high flexibility

Application-specific requirements for future lighting, displays and photovoltaics will include large-area, low-weight and mechanical resilience for dual-purpose uses such as electronic skin, textiles and surface conforming foils. Here we demonstrate polymer-based photovoltaic devices on plastic foil substrates less than 2 μm thick, with equal power conversion efficiency to their glass-based counterparts. They can reversibly withstand extreme mechanical deformation and have unprecedented solar cell-specific weight. Instead of a single bend, we form a random network of folds within the device area. The processing methods are standard, so the same weight and flexibility should be achievable in light emitting diodes, capacitors and transistors to fully realize ultrathin organic electronics. These ultrathin organic solar cells are over ten times thinner, lighter and more flexible than any other solar cell of any technology to date

Surviving fraction (SF) graphs of PC-3 cells.

<p>(<b>A)</b>Note a dose dependent SF curve when PC-3 cell were treated with ¹²C beam only. <b>(B)</b> Effect of different concentration of PNKPi A12B4C3 on SF of PC-3 cells note that cells were least toxic till 10μM concentration.<b>(C-F)</b> Effect of different doses of ¹²C beam (<b>―</b>)with different concentration of A12B4C3 (…..) note a decrease in the SF as the concentration of A12B4C3 increases with ¹²C irradiation.</p