Wu Kuen-Hsien, Li Chong-Wei
Department of Electro-Optical Engineering, Southern Taiwan University of Science and Technology, No. 1, Nan-Tai Street, Yungkang Dist., Tainan 710, Taiwan.
Materials (Basel). 2015 Sep 7;8(9):5922-5932. doi: 10.3390/ma8095283.
Porous-silicon (PS) multi-layered structures with three stacked PS layers of different porosity were prepared on silicon (Si) substrates by successively tuning the electrochemical-etching parameters in an anodization process. The three PS layers have different optical bandgap energy and construct a triple-layered PS (TLPS) structure with multiple bandgap energy. Photovoltaic devices were fabricated by depositing aluminum electrodes of Schottky contacts on the surfaces of the developed TLPS structures. The TLPS-based devices exhibit broadband photoresponses within the spectrum of the solar irradiation and get high photocurrent for the incident light of a tungsten lamp. The improved spectral responses of devices are owing to the multi-bandgap structures of TLPS, which are designed with a layered configuration analog to a tandem cell for absorbing a wider energy range of the incidental sun light. The large photocurrent is mainly ascribed to an enhanced light-absorption ability as a result of applying nanoporous-Si thin films as the surface layers to absorb the short-wavelength light and to improve the Schottky contacts of devices. Experimental results reveal that the multi-bandgap PS structures produced from electrochemical-etching of Si wafers are potentially promising for development of highly efficient Si-based solar cells.
通过在阳极氧化过程中依次调整电化学蚀刻参数，在硅（Si）衬底上制备了具有三层不同孔隙率堆叠PS层的多孔硅（PS）多层结构。这三层PS层具有不同的光学带隙能量，并构建了具有多个带隙能量的三层PS（TLPS）结构。通过在已制备的TLPS结构表面沉积肖特基接触的铝电极来制造光伏器件。基于TLPS的器件在太阳辐射光谱范围内表现出宽带光响应，并对钨灯的入射光获得高光电流。器件光谱响应的改善归因于TLPS的多带隙结构，该结构设计为类似于串联电池的分层配置，用于吸收更宽能量范围的入射太阳光。大光电流主要归因于应用纳米多孔硅薄膜作为表面层来吸收短波长光并改善器件的肖特基接触，从而增强了光吸收能力。实验结果表明，通过对硅片进行电化学蚀刻产生的多带隙PS结构在高效硅基太阳能电池的开发方面具有潜在的应用前景。
