基于非對稱光柵導(dǎo)模共振提高有機太陽能電池吸收效率的研究
發(fā)布時間：2018-09-12 18:58
【摘要】：有機太陽能電池(Organic Solar Cells,OSCs)由于其材料廉價、柔韌性和成膜性都較好、可低溫操作以及可根據(jù)需要對分子進行修飾等特性,近年來,一直成為研究的熱點。雖然有機材料易于制備,但是其較短的載流子擴散距離使得活性層的厚度較大時會降低的載流子收集效率,這一矛盾限制了OSCs器件的吸收,使得OSCs轉(zhuǎn)換效率很低。近年來,有很多研究致力于改變OSCs的內(nèi)部結(jié)構(gòu)以提高活性層對入射光的捕獲能力。在OSCs器件結(jié)構(gòu)中引入金屬納米材料是一種行之有效的方法,例如,在OSCs中引入周期性金屬光柵或在活性層中添加金屬納米顆粒,通過在金屬與有機材料活性層界面形成表面等離子激元,并在局部區(qū)域形成較強的電磁場分布,從而能夠很大程度提高活性層對光的吸收。但是將金屬納米結(jié)構(gòu)與有機活性層直接接觸時,金屬材料會對光生載流子有一定的吸收,同時也會產(chǎn)生熱電子輻射,因此活性層的吸收效率會受到一定的影響。另一方面,在含有一維金屬納米光柵的OSCs器件中,表面等離子激元只有在TM(橫磁場)偏振的入射光下才能激發(fā),而對于TE(橫電場)偏振的入射光,吸收效率并沒有明顯的提高。本論文提出采用電介質(zhì)材料構(gòu)成非對稱光柵來實現(xiàn)OSCs器件吸收效率的提高,具體光柵結(jié)構(gòu)主要由作為活性層的P3HT:PCBM和作為電子傳輸層的PEDOT:PSS材料構(gòu)成。該結(jié)構(gòu)能夠避免因為金屬材料對光生載流子的吸收而產(chǎn)生損耗。在電介質(zhì)材料構(gòu)成的光柵結(jié)構(gòu)中,通過采用合適參數(shù)的衍射光學(xué)元件和波導(dǎo)層的薄膜結(jié)構(gòu)使得衍射光場與受調(diào)制波導(dǎo)泄露模之間耦合引起能量重新分布,從而在波導(dǎo)層產(chǎn)生場強增強的導(dǎo)模共振現(xiàn)象,這種近場的增強能夠促進活性層材料的光的吸收。同時,非對稱光柵能夠打破對稱光柵中的簡并模式,在考察的波長范圍為內(nèi)產(chǎn)生更多的波導(dǎo)模式,從而提高OSCs器件的吸收效率的寬譜特性。本文主要研究內(nèi)容:(1)簡述OSCs的發(fā)展背景和意義,介紹其工作原理、以及影響OSCs活性層的吸收效率的因素。(2)介紹亞波長光柵特性,即導(dǎo)模共振異�，F(xiàn)象。闡述導(dǎo)模共振異常的激發(fā)原理,及如何運用時域有限差分法在TE(橫電場)和TM(橫磁場)偏振模式進行電磁場分析。(3)第三章提出一種基于T型非對稱二元光柵陷光結(jié)構(gòu)的OSCs器件。分析發(fā)現(xiàn),T型對稱光柵結(jié)構(gòu)中,光柵結(jié)構(gòu)的周期P對對稱光柵模式的位置和模式的變化起主要作用。在TE偏振模式下,在400~800 nm范圍內(nèi),與對稱結(jié)構(gòu)相比,與對稱結(jié)構(gòu)相比,含有2個光柵脊的非對稱光柵結(jié)構(gòu)整體平均吸收效率提高了4.2%。與其相比,當非對稱光柵結(jié)構(gòu)中光柵脊的個數(shù)為3個時,整體平均吸收效率提高了約52%。(4)在第三章基礎(chǔ)上,提出核殼-ITO非對稱光柵結(jié)構(gòu)的OSCs器件,發(fā)現(xiàn)核殼-ITO非對稱光柵相比較T型光柵結(jié)構(gòu),導(dǎo)模形成的在有機活性層材料中的局域場分布更有利于器件吸收效率的提高。
[Abstract]:Organic solar cell (Organic Solar Cells,OSCs) has been a hot research area in recent years because of its cheap materials, good flexibility and film-forming properties, low temperature operation and modification of molecules as needed. Although organic materials are easy to prepare, the short carrier diffusion distance reduces the carrier collection efficiency when the thickness of the active layer is larger, which limits the absorption of OSCs devices and makes the conversion efficiency of OSCs very low. In recent years, many studies have been devoted to changing the internal structure of OSCs to improve the ability of the active layer to capture incident light. It is an effective method to introduce metal nanomaterials into the structure of OSCs devices, for example, to introduce periodic metal gratings in OSCs or to add metal nanoparticles to active layers. Through the formation of surface plasmon at the interface of the active layer of metal and organic materials and the formation of strong electromagnetic field distribution in the local region, the absorption of light in the active layer can be greatly improved. However, when the metal nanostructure is directly contacted with the organic active layer, the metal material will absorb the photogenerated carriers and generate hot electron radiation, so the absorption efficiency of the active layer will be affected to a certain extent. On the other hand, in OSCs devices containing one-dimensional metal nanocrystalline gratings, the surface plasma excitations can only be excited under the polarized incident light of TM (transverse magnetic field), but for the incident light polarized by TE (transverse electric field), the absorption efficiency is not significantly improved. In this paper, an asymmetric grating based on dielectric material is proposed to improve the absorption efficiency of OSCs devices. The grating structure is mainly composed of P3HT:PCBM as the active layer and PEDOT:PSS as the electron transport layer. The structure can avoid loss due to the absorption of photogenerated carriers by metal materials. In the grating structure of dielectric material, the coupling between the diffractive light field and the leaky mode of the modulated waveguide is caused by the appropriate parameters of the diffractive optical element and the thin film structure of the waveguide layer, which results in the redistribution of the energy. Thus the guided mode resonance in the waveguide layer is enhanced by the field intensity, and the near field enhancement can promote the light absorption of the active layer material. At the same time, the asymmetric grating can break the degenerate mode in the symmetric grating and generate more waveguide modes in the wavelength range of investigation, so as to improve the absorption efficiency of OSCs devices. The main contents of this paper are as follows: (1) the development background and significance of OSCs, its working principle and the factors affecting the absorption efficiency of the active layer of OSCs are introduced. (2) the characteristics of subwavelength grating, that is, the anomalous phenomenon of guided mode resonance, are introduced. The excitation principle of guided mode resonance anomaly and how to analyze the polarization mode of TE (transverse electric field) and TM (transverse magnetic field) by using finite-difference time-domain method are described. (3) in chapter 3, a novel OSCs device based on T-type asymmetric binary grating trapping structure is proposed. It is found that the periodic P of the grating structure plays a major role in the position and mode change of the symmetric grating mode in the structure of T type symmetric grating. In the polarization mode of TE, the average absorption efficiency of asymmetric grating structure with two ridges is increased by 4.2% compared with symmetric structure in the range of 400,800 nm. Compared with the asymmetric grating structure, when the number of grating ridges is 3, the overall average absorption efficiency is improved by about 52. (4) based on the third chapter, a core-shell OSCs device with asymmetric grating structure is proposed. It is found that the local field distribution of core-shell ITO asymmetric gratings in organic active layer materials is more favorable to the increase of absorption efficiency than that of T-type gratings.
【學(xué)位授予單位】：太原理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TM914.4
本文編號：2239933
[Abstract]:Organic solar cell (Organic Solar Cells,OSCs) has been a hot research area in recent years because of its cheap materials, good flexibility and film-forming properties, low temperature operation and modification of molecules as needed. Although organic materials are easy to prepare, the short carrier diffusion distance reduces the carrier collection efficiency when the thickness of the active layer is larger, which limits the absorption of OSCs devices and makes the conversion efficiency of OSCs very low. In recent years, many studies have been devoted to changing the internal structure of OSCs to improve the ability of the active layer to capture incident light. It is an effective method to introduce metal nanomaterials into the structure of OSCs devices, for example, to introduce periodic metal gratings in OSCs or to add metal nanoparticles to active layers. Through the formation of surface plasmon at the interface of the active layer of metal and organic materials and the formation of strong electromagnetic field distribution in the local region, the absorption of light in the active layer can be greatly improved. However, when the metal nanostructure is directly contacted with the organic active layer, the metal material will absorb the photogenerated carriers and generate hot electron radiation, so the absorption efficiency of the active layer will be affected to a certain extent. On the other hand, in OSCs devices containing one-dimensional metal nanocrystalline gratings, the surface plasma excitations can only be excited under the polarized incident light of TM (transverse magnetic field), but for the incident light polarized by TE (transverse electric field), the absorption efficiency is not significantly improved. In this paper, an asymmetric grating based on dielectric material is proposed to improve the absorption efficiency of OSCs devices. The grating structure is mainly composed of P3HT:PCBM as the active layer and PEDOT:PSS as the electron transport layer. The structure can avoid loss due to the absorption of photogenerated carriers by metal materials. In the grating structure of dielectric material, the coupling between the diffractive light field and the leaky mode of the modulated waveguide is caused by the appropriate parameters of the diffractive optical element and the thin film structure of the waveguide layer, which results in the redistribution of the energy. Thus the guided mode resonance in the waveguide layer is enhanced by the field intensity, and the near field enhancement can promote the light absorption of the active layer material. At the same time, the asymmetric grating can break the degenerate mode in the symmetric grating and generate more waveguide modes in the wavelength range of investigation, so as to improve the absorption efficiency of OSCs devices. The main contents of this paper are as follows: (1) the development background and significance of OSCs, its working principle and the factors affecting the absorption efficiency of the active layer of OSCs are introduced. (2) the characteristics of subwavelength grating, that is, the anomalous phenomenon of guided mode resonance, are introduced. The excitation principle of guided mode resonance anomaly and how to analyze the polarization mode of TE (transverse electric field) and TM (transverse magnetic field) by using finite-difference time-domain method are described. (3) in chapter 3, a novel OSCs device based on T-type asymmetric binary grating trapping structure is proposed. It is found that the periodic P of the grating structure plays a major role in the position and mode change of the symmetric grating mode in the structure of T type symmetric grating. In the polarization mode of TE, the average absorption efficiency of asymmetric grating structure with two ridges is increased by 4.2% compared with symmetric structure in the range of 400,800 nm. Compared with the asymmetric grating structure, when the number of grating ridges is 3, the overall average absorption efficiency is improved by about 52. (4) based on the third chapter, a core-shell OSCs device with asymmetric grating structure is proposed. It is found that the local field distribution of core-shell ITO asymmetric gratings in organic active layer materials is more favorable to the increase of absorption efficiency than that of T-type gratings.
【學(xué)位授予單位】：太原理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TM914.4
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相關(guān)期刊論文 前2條
1 陳樂;王慶康;沈向前;陳文;黃X;劉代明;;Absorption enhancement in thin film a-Si solar cells with double-sided SiO_2 particle layers[J];Chinese Physics B;2015年10期
2 劉瑞遠;孫寶全;;有機物/硅雜化太陽能電池的研究進展[J];化學(xué)學(xué)報;2015年03期
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