Single Grain Boundary Modeling and Design of Microcrystalline Si Solar Cells

Chu-Hsuan Lin,Cheng-Hung Tai,Wen-Tzu Hsu

doi:10.3390/ma6010291

Chu-Hsuan Lin, Cheng-Hung Tai + Show 1 more

Open Access

https://doi.org/10.3390/ma6010291

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Journal: Materials	Publication Date: Jan 21, 2013
Citations: 15	License type: CC BY 4.0

Affiliation: National Dong Hwa University

Abstract

For photovoltaic applications, microcrystalline silicon has a lot of advantages, such as the ability to absorb the near-infrared part of the solar spectrum. However, there are many dangling bonds at the grain boundary in microcrystalline Si. These dangling bonds would lead to the recombination of photo-generated carriers and decrease the conversion efficiency. Therefore, we included the grain boundary in the numerical study in order to simulate a microcrystalline Si solar cell accurately, designing new three-terminal microcrystalline Si solar cells. The 3-μm-thick three-terminal cell achieved a conversion efficiency of 10.8%, while the efficiency of a typical two-terminal cell is 9.7%. The three-terminal structure increased the JSC but decreased the VOC, and such phenomena are discussed. High-efficiency and low-cost Si-based thin film solar cells can now be designed based on the information provided in this paper.

Highlights

Low cost Si-based materials, including microcrystalline silicon and amorphous silicon (a-Si), are promising for use in photovoltaic applications
The low fabrication temperature is suitable for substrates of low cost, low melting points and with a low thermal budget
The fabrication based on hot wire chemical vapor deposition (HWCVD) can lead to a high deposition rate and high open circuit voltage (VOC) [7]

Summary

Introduction

Low cost Si-based materials, including microcrystalline silicon (μc-Si) and amorphous silicon (a-Si), are promising for use in photovoltaic applications. Materials 2013, 6 enhanced chemical vapor deposition (PECVD) and very high frequency plasma-enhanced chemical vapor deposition (VHF PECVD) are usually used to prepare μc-Si thin film solar cells [2,3]. Hot wire chemical vapor deposition (HWCVD) and photochemical vapor deposition (photo-CVD) can be used to deposit μc-Si film at a low fabrication temperature [4,5,6]. The conversion efficiency of solar cells is limited by recombination of photo-generated carriers at dangling bonds of the grain boundary [9]. We investigated the two-terminal and the three-terminal μc-Si solar cells with the same material parameters and device thicknesses, utilizing the simulation tool, Sentaurus TCAD. The AM 1.5G spectrum was weighted by (1-average R) as the input spectrum for Sentaurus to include the reflection or scattering effects

Device Structure

Results and Discussion

Conclusions