Prasad Rajendra M B, Pathan Habib M
Advanced Physics Laboratory, Department of Physics, Savitribai Phule Pune University, Pune 411007, India. National Defence Academy, Khadakwasla, Pune-411023, India.
Nanotechnology. 2016 Apr 8;27(14):145402. doi: 10.1088/0957-4484/27/14/145402. Epub 2016 Feb 26.
In spite of the promising design and architecture, quantum dot sensitized solar cells (QDSSCs) have a long way to go before they attain the actual projected photoconversion efficiencies. Such an inferior performance displayed by QDSSCs is primarily because of many unwanted recombination losses of charge carriers at various interfaces of the cell. Electron recombination due to back electron transfer at the photoanode/electrolyte interface is an important one that needs to be addressed, to improve the efficiency of these third generation nanostructured solar cells. The present work highlights the importance of conformal coverage of CdS quantum dots (QDs) on the surface of the nanocrystalline titania photoanode in arresting such recombinations, leading to improvement in the performance of the cells. Using the successive ionic layer adsorption and reaction (SILAR) process, photoanodes are subjected to different amounts of CdS QD sensitization by varying the number of cycles of deposition. The sensitized electrodes are characterized using UV-visible spectroscopy, cyclic voltammetry and transmission electron microscopy to evaluate the extent of surface coverage of titania electrodes by QDs. Sandwich solar cells are then fabricated using these electrodes and characterized employing electrochemical impedance spectroscopy and J-V characteristics. It is observed that maximum solar cell efficiency is obtained for photoanodes with conformal coating of QDs and any further deposition of sensitizer leads to QD aggregation and so reduces the performance of the solar cells.
尽管量子点敏化太阳能电池（QDSSCs）有着颇具前景的设计和架构，但在达到实际预计的光电转换效率之前，它们仍有很长的路要走。QDSSCs表现出的这种较差性能主要是因为电池各界面处电荷载流子存在许多不必要的复合损失。光阳极/电解质界面处由于背向电子转移导致的电子复合是一个需要解决的重要问题，以提高这些第三代纳米结构太阳能电池的效率。目前的工作突出了在纳米晶二氧化钛光阳极表面对硫化镉量子点（QDs）进行保形覆盖在抑制此类复合方面的重要性，从而提高电池的性能。通过连续离子层吸附和反应（SILAR）工艺，通过改变沉积循环次数，使光阳极受到不同量的硫化镉量子点敏化。使用紫外可见光谱、循环伏安法和透射电子显微镜对敏化电极进行表征，以评估量子点对二氧化钛电极的表面覆盖程度。然后使用这些电极制造夹心式太阳能电池，并采用电化学阻抗谱和J-V特性进行表征。观察到，对于具有量子点保形涂层的光阳极可获得最大的太阳能电池效率，而敏化剂的任何进一步沉积都会导致量子点聚集，从而降低太阳能电池的性能。
