Browsing by Subject "Transfer printing"

Now showing 1 - 3 of 3

Open Access
Synthesis of graphene on ultra-smooth copper foils for large area flexible electronics
(IEEE, 2015) Polat, E. O.; Balcı, Osman; Kakenov, Nurbek; Kocabaş, Coşkun; Dahiya, R.
This work demonstrates the synthesis of high quality, single layer graphene on commercially available ultra-smooth copper foils. The presented method will result in improved scalability of graphene based electronic and optical devices. Our approach is compatible with roll-to-roll printing as well as transfer printing of graphene layers on to a broad range of substrates including flexible and ultra-thin polymers. We propose that using commercially available ultra-smooth coppers provides scalable approach with the reduced variation of transport properties sourced from local graphene quality.
Open Access
Theoretical limits of the multistacked 1-D and 2-D microstructured inorganic solar cells
(SPIE, 2015-08) Yengel, Emre; Karaağaç, H.; Logeeswaran, V. J.; İslam, M. S.
Recent studies in monocrystalline semiconductor solar cells are focused on mechanically stacking multiple cells from different materials to increase the power conversion efficiency. Although, the results show promising increase in the device performance, the cost remains as the main drawback. In this study, we calculated the theoretical limits of multistacked 1D and 2D microstructered inorganic monocrstalline solar cells. This system is studied for Si and Ge material pair. The results show promising improvements in the surface reflection due to enhanced light trapping caused by photon-microstructures interactions. The theoretical results are also supported with surface reflection and angular dependent power conversion efficiency measurements of 2D axial microwall solar cells. We address the challenge of cost reduction by proposing to use our recently reported mass-manufacturable fracture-transfer- printing method which enables the use of a monocrystalline substrate wafer for repeated fabrication of devices by consuming only few microns of materials in each layer of devices. We calculated thickness dependent power conversion efficiencies of multistacked Si/Ge microstructured solar cells and found the power conversion efficiency to saturate at %26 with a combined device thickness of 30 μm. Besides having benefits of fabricating low-cost, light weight, flexible, semi-transparent, and highly efficient devices, the proposed fabrication method is applicable for other III-V materials and compounds to further increase the power conversion efficiency above 35% range. © 2015 SPIE.
Open Access
Weighing graphene with QCM to monitor interfacial mass changes
(American Institute of Physics Inc., 2016) Kakenov, N.; Balci, O.; Salihoglu, O.; Hur, S. H.; Balci, S.; Kocabas, C.
In this Letter, we experimentally determined the mass density of graphene using quartz crystal microbalance (QCM) as a mechanical resonator. We developed a transfer printing technique to integrate large area single-layer graphene on QCM. By monitoring the resonant frequency of an oscillating quartz crystal loaded with graphene, we were able to measure the mass density of graphene as ∼118 ng/cm2, which is significantly larger than the ideal graphene (∼76 ng/cm2) mainly due to the presence of wrinkles and organic/inorganic residues on graphene sheets. High sensitivity of the quartz crystal resonator allowed us to determine the number of graphene layers in a particular sample. Additionally, we extended our technique to probe interfacial mass variation during adsorption of biomolecules on graphene surface and plasma-assisted oxidation of graphene.