Susha N, Nandakumar K, Nair Swapna S
Dept. of Physics, Central University of Kerala Kasaragod India - 671314.
International and Inter University Centre for Nanoscience and Nanotechnology, Mahatma Gandhi University Kottayam India - 686 560
RSC Adv. 2018 Mar 21;8(21):11330-11337. doi: 10.1039/c7ra13116j.
Development of novel materials for thin film solar cells are gaining significant attention due to their tunable wide bandgap and extensive application potential in flexible energy harvesters. CdS is a known window material for thin film solar cells. Tuning of the photoconductivity of CdS by doping, substitution and grain size tailoring is widely attempted by researchers. Inorganic core/shell structures like CdS/CdSe, CdS/ZnS are other possible candidates with band gap tailorability. However, such attempts are rare in tailoring the photoconductivity by providing an organic shell over the inorganic core. Here the authors synthesised CdS/betanin core/shell structures using wet chemical routes. Spectroscopic studies show that the composite structure is core/shell like, with CdS as the core and betanin (a natural dye), as the outer shell with an average core particle size of 10 nm. The absorption spectra of the composite system show the signature of an additional band in the lower wavelength region and it is redshifted with increase in betanin percentage. The intermediate band observed in the energy of ∼1.75 eV, helps CdS to enhance the rate of absorption. Simultaneous absorbance of lower and higher energy photons from the solar radiation can increase the efficiency of CdS based solar cells. A huge enhancement in conductivity is observed in CdS/betanin composites on illumination with white light due to the transfer of photogenerated electrons from the conduction band of betanin dye to the conduction band of CdS.
由于其可调节的宽带隙以及在柔性能量收集器中的广泛应用潜力，用于薄膜太阳能电池的新型材料的开发正受到广泛关注。硫化镉（CdS）是一种已知的薄膜太阳能电池窗口材料。研究人员广泛尝试通过掺杂、替代和调整晶粒尺寸来调节CdS的光电导率。像CdS/CdSe、CdS/ZnS这样的无机核/壳结构是具有带隙可定制性的其他可能候选材料。然而，通过在无机核上提供有机壳层来定制光电导率的此类尝试很少见。在此，作者采用湿化学路线合成了CdS/甜菜红素核/壳结构。光谱研究表明，该复合结构为核/壳状，以CdS为核，甜菜红素（一种天然染料）为外壳，平均核粒径为10纳米。复合体系的吸收光谱在较低波长区域显示出一个附加带的特征，并且随着甜菜红素百分比的增加而发生红移。在约1.75电子伏特能量处观察到的中间带有助于CdS提高吸收速率。同时吸收来自太阳辐射的低能和高能光子可以提高基于CdS的太阳能电池的效率。由于光生电子从甜菜红素染料的导带转移到CdS的导带，在白光照射下，CdS/甜菜红素复合材料的电导率有巨大提高。
