Enhanced light trapping based on guided mode resonance effect for thin-film silicon solar cells with two filling-factor gratings

Abstract

An approach of enhanced light-trapping in a thin-film silicon solar cell by adding a two-filling-factor asymmetric binary grating on it is proposed for the wavelength of near-infrared. Such a grating-on-thin-film structure forms a guided-mode resonance notch filter to couple energy diffracted from an incident wave to a leakage mode of the guided layer in the solar cell. The resonance wave coupled between two-filling-factor gratings would laterally extend the optical power and induce multiple bounces within the active layer. The resonance effect traps light in the cell enhancing its absorption probability. A dynamic light-trapping behaviour in solar cells is observed. A photon dwelling time is proposed for the first time to quantify the light-trapping effect. Moreover, the light absorption probability is also quantified. As compared the grating-on-thin-film structure with the one of planar silicon thin film, simulation results reveal that it is 3-fold enhancement in the light absorption within a spectral range of 920-1040 nm. Moreover, such an enhancement can be maintained even the incident angle of near-IR broadband light wave varies up to +/-40 degrees.

Light management through guided-mode resonances in thin-film silicon solar cells

“…Numerous studies have been conducted to improve light-capture and collection efficiency of thin absorbing layers. The application of diffractive optics, [4][5][6] random texturing, 7,8 antireflective layers, 9,10 plasmonics, [11][12][13] photonic crystals, [14][15][16] guided-mode excitation, 6,17,18 and three-dimensional structures like nanowire, nanodome, and nanocone solar cells [19][20][21] shows distinguished improvements in solar absorption. Though each mechanism contributes to the manipulation of optical path lengths inside the films, the most efficient light-harvesting scheme is yet to be convincingly identified.…”

Colloidal self-assembly concepts for light management in photovoltaics

“…In Fig. 5(b) we show the four most common modes, which could enhance light absorption in the spectral region for solar cell applications: (1) a Fabry-Perot standing-wave resonance [10,21,144], (2) guided resonance of the semiconductor material [145][146][147], (3) grating coupling along the periodic structure [148,149], and (4) Whispering gallery mode when a wavelengthscale dielectric sphere is in close contact to a high-index substrate [77,150]. These modes or a combination of them, which leads to hybridization, can occur in thin film solar cells.…”

Enhanced Absorption Efficiency of Solar Cells Using Guided-mode Resonance

“…이 같은 특성을 이용하면 특정 파장에서 빛의 투과를 제한하거나 반대로 빛의 반사를 제한하는 데 응용할 수 있으 며, 때문에 주로 광 필터에 관한 연구가 진행되어 왔다 [8,9,10] . 최근에는 도파모드 공진 특성을 이용하면 광자가 유전체를 따라 진행하게 되므로 상대적으로 얇은 두께의 유전체 층을 사용하더라도 흡수에 충분한 광자의 이동경로를 확보할 수 있게 된다는 사실 때문에 태양전지 분야에서도 다양한 연구 가 진행되고 있다 [11] . [12,13,14] .…”