Abstract
The photovoltaic (PV) market today is dominated by silicon (Si)-based solar cells, which, however, can be improved in performance and cost by developing technologies that use less material. We propose an indium phosphide (InP) nanoresonator array on silicon ultra-thin film with a combined thickness of 0.5 μm to 2 μm as a solution to minimize cost and maximize power efficiency. This paper focuses on simultaneously achieving broadband antireflection and enhanced absorption in thin-film Si with integrated InP nanodisk arrays. Electromagnetic simulations are used to design and optimize the reflectance and absorption of the proposed design. By varying the height and radius of the InP nanodisks on the Si substrate, together with the array pitch, a weighted reflectance minimum, with respect to the AM1.5 solar spectrum, of 2.9% is obtained in the wavelength range of 400 nm to 1100 nm. The antireflective properties are found to be a combination of a Mie-resonance-induced strong forward-scattering into the structure and an effective index-matching to the Si substrate. In terms of absorption, even up to 2 μm from the Si surface the InP nanodisk/Si structure consistently shows superior performance compared to plain Si as well as a Si nanodisk/Si structure. At a depth of 500 nm from the surface of the substrate, the absorption values were found to be 47.5% for the InP nanodisk/Si structure compared to only 18.2% for a plain Si substrate. This shows that direct bandgap InP nanoresonator arrays on thin-film Si solar cells can be a novel design to enhance the absorption efficiency of the cell.
Highlights
Si solar cells require thick active layers, typically in excess of a few 100 μm due to inefficient absorption of light in Si compared to 1 μm to 2 μm indirect bandgap materials such as gallium arsenide (GaAs) or indium phosphide (InP) [1]
The effect of size and pitch/period of the array of InP nanodisks on the reflectance from the substrate was studied using finite-difference time-domain (FDTD) simulations
A reflectance minimum of 2.9% was found for a hexagonal InP nanodisk array on a Si substrate with parameters: height 120 nm, pitch 250 nm and radius 80 nm
Summary
Solar cell production is dominated today by silicon (Si)-based technology, mainly due to its high efficiency and mature production methods as well as the abundance and non-toxicity of Si. Si solar cells require thick active layers, typically in excess of a few 100 μm due to inefficient absorption of light in Si compared to 1 μm to 2 μm indirect bandgap materials such as gallium arsenide (GaAs) or indium phosphide (InP) [1]. Most commonly encountered low-cost thin-film solar cells use materials such as amorphous silicon (a-Si), Indium Phosphide (InP), Cadmium Telluride (CdTe), and Copper Indium Gallium Selenide (CIGS). The thickness of these cells ranges from a few to tens of micrometers compared to a typical thickness of 200 μm to 500 μm of a c-Si solar cell. With an efficiency of 26.1% c-Si is still leading the race [2–4]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
