Abstract:
In the planar heterostructure of perovskite-based solar cells (PSCs), tin oxide (SnO2) is a material that is often used as the electron transport layer (ETL). SnO2 ETL exhibits favorable optical and electrical properties in the PSC structures. Nevertheless, the open circuit voltage (VOC) depletion occurs in PSCs due to the defects arising from the high oxygen vacancy on the SnO2 surface and the deeper conduction band (CB) energy level of SnO2. In this research, a cerium (Ce) dopant was introduced in SnO2 (Ce-SnO2) to suppress the VOC loss of the PSCs. The CB minimum of SnO2 was shifted closer to that of the perovskite after the Ce doping. Besides, the Ce doping effectively passivated the surface defects on SnO2 as well as improved the electron transport velocity by the Ce-SnO2. These results enabled the power conversion efficiency (PCE) to increase from 21.1% (SnO2) to 23.0% (Ce-SnO2) of the PSCs (0.09 cm2 active area) with around 100 mV of improved VOC and reduced hysteresis. Also, the Ce-SnO2 ETL-based large area (1.0 cm2) PSCs delivered the highest PCE of 22.9%. Furthermore, a VOC of 1.19 V with a PCE of 23.3% was demonstrated by Ce-SnO2 ETL-based PSCs (0.09 cm2 active area) that were treated with 2-phenethylamine hydroiodide on the perovskite top surface. Notably, the unencapsulated Ce-SnO2 ETL-based PSC was able to maintain above 90% of its initial PCE for around 2000 h which was stored under room temperature condition (23-25 °C) with a relative humidity of 40-50%.
摘要:
在基于钙钛矿的太阳能电池(PSC)的平面异质结构中,氧化锡(SnO2)是经常用作电子传输层(ETL)的材料。SnO2ETL在PSC结构中表现出良好的光学和电学性质。然而,由于SnO2表面上的高氧空位和SnO2的较深导带(CB)能级引起的缺陷,在PSC中发生开路电压(VOC)耗尽。在这项研究中,在SnO2(Ce-SnO2)中引入铈(Ce)掺杂剂以抑制PSC的VOC损失。Ce掺杂后,SnO2的CB最小值更接近钙钛矿的CB最小值。此外,Ce掺杂有效地钝化了SnO2上的表面缺陷,并通过Ce-SnO2提高了电子输运速度。这些结果使得功率转换效率(PCE)能够从PSC(0.09cm2有效面积)的21.1%(SnO2)增加到23.0%(Ce-SnO2),具有约100mV的改进的VOC和减小的滞后。此外,基于Ce-SnO2ETL的大面积(1.0cm2)PSC递送22.9%的最高PCE。此外,1.19V的VOC和23.3%的PCE通过在钙钛矿顶表面上用2-苯乙胺氢碘化物处理的Ce-SnO2ETL基PSC(0.09cm2活性面积)证明。值得注意的是,未包封的基于Ce-SnO2ETL的PSC能够保持其初始PCE的90%以上约2000小时,其在相对湿度为40-50%的室温条件(23-25°C)下储存。