Color Glass by Layered Nitride Films for Building Integrated Photovoltaic (BIPV) System
Round 1
Reviewer 1 Report
The authors report about the experimental results of the transmittance and reflectance of thin interference layers on ITO (indium-tin-oxide) coated glass. It is suggested that these coated glasses can be used for colored building facades with integrated photovoltaic power generators. So far the subject fits pretty well into the actual clean energy research attempting to meet the high architectural demands for building facades. However from the manuscript it remains unclear in what way the results will contribute to a future advancement. Colored photovoltaic facades for building integration have a long tradition. For crystalline silicon (c-Si) solar cells the top typically is covered with a quarter-wavelength antireflective (AR) layer of suitable index of refraction which serves for both: (i) a reduction of the optical surface reflectance losses of the cells and (ii) for the reduction of electrical surface recombination called passivation. Typical dielectrics are silicon-nitride but also aluminum nitride and similar materials have been suggested and investigated. By the variation of the AR layer's thickness different color appearances of the c-Si solar cells could be achieved without additional processes. For thin film solar cells, based i.e. on dye sensitizers or organic solids which quite often appear semitransparent the use of colored cover glasses or a painted background may be used.
1) Introduction
Purpose of the present work together with the state of previous research which I expect in the introduction was not found in the manuscript.
2) Materials and Methods
Fig.1 does neither represent the sequence of optical layers used in the simulation nor in the experiments. From the experiments I understand that 4 (instead of 2 shown) cases, as given by M1 - M4 were investigated: From bottom to top (i) glass- 150 nm ITO – 30nm TiN – 30nm AlN (ii) glass- 150 nm ITO – 30nm TiN – 50nm AlN (iii) glass- 150 nm ITO – 30nm TiN – 30nm AlN – 30nm TiN (iv) glass- 150 nm ITO – 30nm TiN – 50nm AlN – 30nm TiN. Why these cases are not clearly shown in fig.1 and referred to in the further text as M1 … M4? Instead a layer sequence which was not experimentally investigated is shown on the left side of fig.1. But the case where 3 layers were deposited is ignored in the illustration.
3.1) Simulation and Analyses
In this sub-section two model calculations named A and B were presented. However nothing is said about (i) what layers were included and which parameter (or which thickness) was varied and what parameters were kept constant at (iii) what thickness in order to obtain the graphs shown in fig.3
The principle of constructive and destructive interference of light-waves given by the authors on page 5 is causing rather confusion than enlightenment. Citing an appropriate introduction to wave optics (i.e. the references in http://www.u.arizona.edu/~waisze/report.html ) together with the consequence, that by varying the optical thickness (or optical path) the peaks in reflectance/transmittance spectra can be shifted such that “any visible color” can be adjusted.
Author Response
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Author Response.pdf
Reviewer 2 Report
The paper titled Color Glass by Layered Nitride Films for Building Integrated
Photovoltaic (BIPV) System deals with recently very popular topic of BIPV system. Authors investigate different layer thickness combinations of AlN/TiN and TiN/AlN bilayers deposited onto glass substrates and considered their optical properties. Finally they fabricated some samples and determined their transmittance spectra.
The paper is well organized, however during review I found some points that have to be adressed before the publication:
- line 7 - incomplete affiliation, Republic of ?
- lines 71-72: However, its major limitation is slow growth rate, hence expensive to be considered for large area commercial applications in BIPV systems. Please add information about typical growth rate with ALD method and compare it with typical deposition rate when magnetron sputtering is used.
- Introduction - what is a typical side of industrial ALD reactor and magnetron sputtering system. What is expected consumption of reagents in the case of ALD and targets/gases in the case of sputtering necessary for fabrication of 100 m2 of BIPV glass?
- 2. Materials and Methods - please provide information about used magnetron sputtering system, producer, model ...
- Fig 2 - the information about refractive index of TiN are insufficient. There is a lot of commonly available databases with such data, please improve the presented results of n for TiN using for example https://refractiveindex.info/?shelf=main&book=TiN&page=Pfluger
- line 182, 183 - repeated sentences
- Fig 6 - are you able to provide reflection spectra of analysed samples?
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
The manuscript “Color Glass by Layered Nitride Films for Building Integrated Photovoltaic (BIPV) System” presents the coloration of glass slides using thin film deposition (RF sputtering).
- The presented results are correct but it is no data referred to as photovoltaic applications.
- I strongly recommend extending the manuscript to a least of the simulation of the proposition of the photovoltaic device structure.
- The Authors present the transmittance in Fig. 6. What is the reflection vs. angle of incident light rays?
- What are the advantages of the proposed solution since glass (n=c.a. 1.5) has a transmittance of 92%?
- Why the Authors measure only the VIS spectrum when the 950 UV-vis-NIR spectrophotometer is available. The maximum of typical silicon PV photodione is 800-1000nm.
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
I really appreciate the corrections made by authors. Now, after corrections the paper is suitable for publishing in Crystals.
Reviewer 3 Report
The manuscript: Color Glass by Layered Nitride Films for Building Integrated Photovoltaic (BIPV) System can be acceptedfor publication in the present form.
