Amorphous silicon solar cells on nano‐imprinted commodity paper without sacrificing efficiency

Abstract

Paper is a cheap substrate which is in principle compatible with the process temperature applied in the plasma enhanced chemical vapour deposition (PECVD) and hot wire CVD (HWCVD) of thin film silicon solar cells. The main drawback of paper for this application is the porosity due to its fibre like structure. The feature size (micrometre scale) is larger than the thickness of the applied photovoltaic layers. To overcome this problem, UV curable lacquer was used to planarize the surface. Plain 80 grams printer paper was taken as a substrate and the lacquer smoothens the rough surface of the paper such that a designed nanostructure can be imprinted for light scattering. In this manner single junction amorphous silicon solar cells with a HWCVD deposited intrinsic layer were processed on paper, without any concessions to the process temperature of 200 °C. The cell performance is comparable to that of reference cells grown on stainless steel, proving that solar cells can be deposited on paper substrates without sacrificing performance. PV on paper could be applied as ”disposable” power source for gadgets, electronic labelling, remote sensing systems, etc. (Internet of Things). (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)

Silicon Thin Films: Functional Materials for Energy, Healthcare, and IT Applications

“…In Summary: The implementation of cheap and flexible substrates such as various plastics, cellulose, and cellophane foils for thin film solar cells is a hot topic that opens a wide range of novel applications where flexibility is needed, including portable power, integration into clothing and packaging. For thin film silicon solar cells manufactured on these flexible substrates the reported efficiencies are in the range of 5–7%, which is still lower than traditional thin film silicon solar cells manufactured on rigid glass substrates. Nevertheless, flexible thin film silicon solar cells can offer valuable advantages such as light weight, flexibility, and bendability, and low cost.…”

“…Such high preparation temperatures are incompatible with polymer substrates, therefore the challenge is to combine low temperature flexible substrates with existing high temperature TCO textures. This can be achieved by utilizing a nanoimprint process, which is fully compatible with both polymer and paper flexible substrates . Figure shows the SEM images of the glass and flexible PET substrates covered by ZnO:Al with nanoimprinted textures.…”

Printed Solar Cells and Energy Storage Devices on Paper Substrates

“…As already reported in Section 2, the main challenge in the fabrication of paper based solar cell is the deposition of the bottom electrode on cellulose due to roughness and porosity. [9,59,63,[99][100][101] In order to produce successful devices deposited on paper, the first active layer, the bottom electrode, needs to be a high quality homogeneous, thin and crack -free layer. Researchers implemented four different methods to deposit bottom electrodes on rough substrates: 1)…”

“…Optimization of bottom electrode deposition avoiding or exploiting the surface structure, [50,[102][103][104] 2) modification of the paper surface by using planarization layers, [42,99] 3) use of nanocellulose substrate with smooth surface, [70,101] and 4) development of conductive cellulose substrates. [63] Once the bottom electrode is successfully deposited, the electron/hole transport, active and hole/electron transport layers are deposited following the same procedures used in the control/reference cells on glass or plastic substrates.…”

Flexible thin film solar cells on cellulose substrates with improved light management

“…In this work, we present a concept based on UV nanoimprint lithography of a textured surface on cellulose based substrates. In contrast to commonly smooth and small feature substrates (such as, for example, periodic textures and Asahi type textures), we demonstrated the application of random textures, in particular a texture with huge surface features as obtained in the case of state‐of‐the‐art textured ZnO:Al , on a on cellulose substrate. This also opens the field to a wider range of applications especially once multijunction solar cells are considered , when the applied structures are more flexible.…”