Large Absorption Enhancement in Ultrathin Solar Cells Patterned by Metallic Nanocavity Arrays.

Wei Wang,Xiaozhou Che,Jiasen Zhang,Guogang Qin

doi:10.1038/srep34219

Wei Wang, Xiaozhou Che + Show 2 more

Open Access

https://doi.org/10.1038/srep34219

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Abstract

A new type of light trapping structure utilizing ring-shaped metallic nanocavity arrays is proposed for the absorption enhancement in ultrathin solar cells with few photonic waveguide modes. Dozens of times of broadband absorption enhancement in the spectral range of 700 to 1100 nm is demonstrated in an ultrathin Si3N4/c-Si/Ag prototype solar cell by means of finite-difference time-domain (FDTD) simulation, and this dramatic absorption enhancement can be attributed to the excitation of plasmonic cavity modes in these nanocavity arrays. The cavity modes optimally compensate for the lack of resonances in the longer wavelength range for ultrathin solar cells, and eventually a maximum Jsc enhancement factor of 2.15 is achieved under AM 1.5G solar illumination. This study opens a new perspective for light management in thin film solar cells and other optoelectronic devices.

Highlights

Until now, more than 86% of the solar cell market is still based on crystalline silicon wafers[2], which account for around 24% of the total cost of the corresponding solar modules[3]
This structure represents a typical problem in ultrathin solar cells lacking in waveguide mode resonance, since the 100 nm thick c-Si layer here supports only the lowest order photonic waveguide mode in the wavelength range of 700 to 1100 nm
In the above design and simulations, a new type of light trapping scheme utilizing ring-shaped plasmonic nanocavity arrays for the absorption enhancement in ultrathin solar cells is proposed, and the absorption enhancement in ultrathin 50 nm Si3N4/100 nm c-Si/Ag prototype solar cells patterned by various nanocavity arrays is studied using finite-difference time-domain (FDTD) simulation

Summary

Introduction

More than 86% of the solar cell market is still based on crystalline silicon wafers[2], which account for around 24% of the total cost of the corresponding solar modules[3]. A variety of deliberate designs of plasmonic[10,11,12,13,14,15,16,17,18,19] and photonic[20,21,22,23,24,25,26,27,28] nanostructures have been proposed, which can couple and bind light into photovoltaic active regions efficiently, providing ideal building blocks for the realization of novel and efficient solar cells with much thinner cell thickness. Solar cells with thicknesses comparable to minority carrier diffusion lengths usually support few waveguide modes, especially for longer wavelengths. The evanescent nature and strong field enhancement of SPPs can be sufficiently employed, making it possible to greatly improve the poor absorption of ultrathin solar cells suffering from deficient photonic waveguide mode resonance. The simulation routine facilitates the identification of different resonances together with knowledge on their origin, which enables a more thoughtful and effective optimization of the overall absorption of sunlight[9]

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Results

Conclusion