1. Green Phtonics Lab., National Chiao Tung University
Optical Absorption Enhancement in Silicon Nanohole Arrays for Solar Photovoltaics
Sang Eon Han and Gang Chen*
Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
Reporter: Bo-Yu Huang
Advisor: Peichen Yu
Green Phtonics Lab., National Chiao Tung University
2018/11/19
2018/11/19 1

2. Outline Introduction Simulation & Discussion Summary Nanorod arrays
Nanohole arrays
Simulation & Discussion
Summary

3. Introduction
Poor infrared absorption of crystalline silicon (indirect band gap)
µm c-Si active layers that absorb light efficiently
This thickness accounts for ∼ 40% of the total cost
An effective technique for light trapping in thin active layers needs to be developed

4. Introduction Nanorod arrays
Construct a p-n or a p-i-n junction in the radial direction of each nanorod
Shorten the carrier diffusion length
Anti-reflection

5. Introduction Nanohole arrays
We find that nanohole arrays are comparable to or even better than nanorod arrays in terms of light absorption.

6. Introduction Silicon nanohole arrays exhibit better absorption
Applied physics letter, 96, (2010)
Here, we are intersting in silicon nanohole. Because
At 2010, some researches have shown that silicon nanohole behave better light absorption than film or nanowire.
On the other hand, nanowire or nanohole solar cell with radial pn junction could shorten the diffusion length. In fact, beside the better absorption, nanohole have stronger mechanical robustness. Make it easier to fabricate and have more applications.
Nano letters,10, 1082 (2010)
JACS, 132, 6872 (2010)
Silicon nanohole arrays exhibit better absorption
and mechanical robustness 6 6

7. Simulation & Discussion
For rod:
Filling fraction=

8. Simulation & Discussion
Absorption is higher for the nanohole array when λ is less than approximately 750 nm

9. Simulation & Discussion
thickness is 2.33 µm

10. Summary
We have presented the optical properties of c-Si nanohole array structures and found that their absorption is better than nanorod arrays.
Nanohole array structure requiring one-twelfth the c-Si mass and one-sixth the thickness of a standard 300 µm Si wafer.

11. Thanks for your attention!!
2018/11/19

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2018/11/19