MICRO METROLOGY | ARTICLE
With 3D confocal laser scanning microscopy, it is the laser that scans the surface, and such a non-contact approach achieves a great level of accuracy (figure 2). Moreover, providing a visual image of the sample is more intuitive, and with the LEXT OLS4100 this information is easily compiled into a report, presenting the image to support numerical data.
Investigating transparent electrodes: an alternative to ITO
Combining optical transparency with conduction, transparent electrodes form the anode of the solar cell while also allowing light to pass through to the active layer. Te rapidly diminishing resource of ITO is currently the industrial standard for transparent electrodes. Moreover, ITO is a britle material, restricting its use in mechanically flexible devices, and the hunt is on for a lightweight, cheap, flexible alternative that is also compatible with large- scale processing.
One promising alternative is a mesh of silver nanowires (AgNWs) embedded in a polymer matrix, and Dr Schiek’s laboratory is working on their production and integration into organic solar cells. For optimum conductivity, a uniform connection must exist between the active later and electrode, demanding a homogenous AgNW mesh. However, this is challenging to achieve across the whole solar cell using current spin-coating production techniques, and surface roughness evaluation plays a central role in optimising the synthesis protocol.
AFM has been the main technique employed for the surface roughness evaluation of the AgNW mesh, but the introduction of the LEXT OLS4100 has vastly improved the efficiency of this. Firstly, Dr Schiek found that expanding the field of view using the image stitching function allowed her to view a more representative sample of the electrode surface. Te AgNW mesh may appear regular on a smaller scale, but by creating high-resolution images of one mm2 (10 times greater than possible with AFM), regions of aggregation are easily identified that would otherwise have been missed (figure 3A). As can be seen in figure 3B, the soſtware also allows the height profile to be visualised in 3D, useful for both analysis and documentation. Moreover, the ability to increase the low-pass filter from a height of 80 µm to 800 µm allows more insightul analysis of the elevated regions of the silver nanowires.
It is also the case that AFM is time consuming. Not only does the scan itself take up to an hour, aſter seting up the instrument and adjusting for tip-related artefacts, it can oſten take a whole day to acquire a single useful image. With 3D CLSM, image acquisition is rapid and also highly intuitive owing to the dedicated soſtware, even for students lacking microscopy experience. In terms of performance, the researchers found that CLSM with the LEXT OLS4100 produced results comparable with AFM, and have benefited from the improved efficiency of surface roughness evaluation of transparent electrodes.
WATCH INDUSTRY JEWELLERY MEDICAL DENTAL AVIATION / AEROSPACE MICROMECHANICS
HIGH PRECISION MACHINING CENTRES
>> Continued on page 22
WILLEMIN-MACODEL SA CH-2800 DELÉMONT
WWW.
WILLEMIN-MACODEL.COM
21 | commercial micro manufacturing international Vol 7 No.6
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52