超薄ALD层包覆TiO2光阳极增加量子点太阳能电池的量子点吸附量和电荷收集效率(英文)

Ultrathin ALD coating on TiO_2 photoanodes with enhanced quantum dot loading and charge collection in quantum dots sensitized solar cells

TiO_2纳米晶体具有稳定的化学性质和合适的能带结构,因而被广泛应用在量子点太阳能电池的光阳极材料中.但是,其较多的表面缺陷和颗粒边界引起的严重复合限制了电池效率.本文利用原子层沉积法(ALD)在TiO_2光阳极膜上沉积一层超薄TiO_2层.实验结果表明,这层超薄TiO_2层不仅减少了表面缺陷,改善了颗粒间的连接性,阻止了复合的发生,提高了电子收集效率,而且通过表面能的提升,量子点的吸附量增加,光捕获效率(LHE)也得以提高.因此,基于ALD修饰的TiO_2膜制备的太阳能电池的效率达5.07%,明显优于没有ALD修饰的电池(4.03%).

TiO_2 nanocrystals are widely used in photoanodes for quantum dot solar cells(QDSCs) owing to their chemical stability and suitable energy band structure.However, surface defects and grain boundaries of TiO_2 nanocrystals photoanodes allow high surface charge recombination,which limits the performance of QDSCs. In this work, an ultrathin TiO_2 layer is introduced to the surface of TiO_2 photoanodes by atomic layer deposition(ALD).The ultrathin layer not only reduces the surface defects of TiO_2 nanoparticles and strengthens the connection between adjacent nanoparticles to suppress the charge recombination for improving the electron collection efficiency(ηcc), but also increases the surface energy of photoanodes to load more quantum dots(QDs) for enhancing the light harvesting efficiency(LHE). As a result, the solar cell based on CdS/CdSe QDs with ALD treatment exhibits an efficiency of 5.07% that is much higher than that of the cells without modification(4.03%).