Cost-effective Fabrication of Transparent Electrode with Embedded Metal Mesh for Flexible Organic Solar Cells Arshad Khan1, Yu-Ting Huang1, Sangeon Lee2, Taehee Jang3, Ze Xiong4, Cuiping Zhang1,5, Peng Zhai1, Jinyao Tang4, L. Jay Guo2,3, Shien-Ping Feng1 and Wen-Di Li1,5 1Department
of Mechanical Engineering, 4Department of Chemistry, The University of Hong Kong, Hong Kong , China 2Department of Mechanical Engineering, 3Department of Electrical Engineering and Computer Science, The University of Michigan, Ann Arbor, USA 5HKU-Shenzhen Institute of Research and Innovation (HKU-SIRI), Shenzhen, China (contact email:
[email protected]) 1. Introduction
5. Dimensional Scalability of EMTEs (Cont’d.)
3. Prototype Copper EMTEs (50 µm pitch) Morphology Characterization
Objective of the Research To fabricate metal-mesh transparent electrodes with superior performance in terms of low sheet resistance, good optical transparency, enhanced flexibility and longterm stability. To develop a non-vacuum, solution-processed and lowcost fabrication techniques for transparent conductive electrodes (TCEs). To apply the metal-mesh transparent electrodes for range of flexible solar cells, displays, touch panels, and other optoelectronic devices.
COC Cu
Mesh Pattern on FTO Glass
2. Schematic Illustration of the EMTE Fabrication Resist Mesh Pattern on FTO Glass
Electroplated Cu Mesh on FTO Glass
Cu Mesh Transferred and Embedded in COC Film
Performance Characterization and Stability Tests
Optical Transmittance Spectra
Figure of Merit (FoM) for EMTEs
Cu Mesh Embedded in COC Film
Cu Mesh on FTO Glass
6. EMTEs Based Flexible Dye Sensitized Solar Cells
FoM of TCEs in Current Literature Photovoltaic Performance of Different Cathode Substrates Front Illumination
Anode
Compressive Loading
Tensile Loading
Chemical Stability Tests
4. Material Versatility and Dimensional Scalability of EMTEs
Cathode
Back Illumination
Jsc
(mA/cm2)
Voc (V)
FF (%)
η (%)
Jsc
(mA/cm2)
Voc (V)
FF (%)
η (%)
ITO PEN Low-temperature Paste
Ni Mesh EMTEs
11.63
0.70
0.68
5.52
9.98
0.70
0.67
4.71
ITO PEN
8.76
0.74
0.66
4.31
4.11
0.75
0.69
2.11
Ti Foil High-temperature Paste
Ni Mesh EMTEs
13.19
0.79
0.67
6.91
8.84
0.79
0.66
4.57
ITO PEN
Not Applicable
7. Summary We report a new structure of flexible transparent electrodes, featuring a metal mesh fully embedded and mechanically anchored in a flexible substrate and a cost-effective solution-based fabrication strategy for this new transparent electrode. The embedded nature of the metal-mesh electrodes provides a series of advantages, including surface smoothness that is crucial for device fabrication, mechanical stability under high bending stress, strong adhesion to the substrate with excellent flexibility, and favorable resistance against moisture, oxygen, and chemicals. Various prototype flexible transparent electrodes are fabricated with transmittance higher than 90% and sheet resistance below 1 ohm sq− 1 , as well as extremely high figures of merit up to 1.5 × 104 , which are among the highest reported values in recent studies.
Prototype EMTEs of Various Metals
The University of Hong Kong
High-Transmittance EMTE
Cu Mesh EMTE (150µm pitch)
Finally using our embedded metal-mesh electrode, flexible dye sensitized solar cells are fabricated with both ITO-PEN and Ti foil as anode substrate, demonstrating the high power conversion efficiency of 6.91% in back-illumination.