基于一种简单的光退火方法的高效倒置型聚合物太阳电池

Efficient Inverted Polymer Solar Cells Based on A Simple Photo-annealing Method

介绍了一种简单的光退火提高倒置型聚合物太阳电池效率的方法。通过采用易于溶液加工的Cs2CO3作为电子传输层,在光退火15 min之后,器件的光电转换效率达到了8.35%,其中短路电流密度为15.8 mA/cm2,开路电压为0.76 V,填充因子为69.5%。该填充因子是目前基于PTB7聚合物太阳电池的最高填充因子。X射线光电子能谱结果显示,Cs2CO3在光退火的过程中转变为了Cs2O与CO2。为了验证该机制,采用不同辐照时间的Cs2CO3作为电子传输层,所得到的光伏器件的效率几乎与光退火时相同。此外,通过真空热蒸发Cs2CO3作为电子传输层,也几乎得到了和光退火条件下同样的光电转换效率。上述结论证明光退火是一种非常有效的、简单的提高聚合太阳电池效率的方法。

An interesting photo-annealing phenomenon has been successfully demonstrated in poly-mer solar cells ( PSCs ) with an inverted device architecture by employing solution processable Cs2 CO3 as electron extraction layer. As the photo-annealing time attained 15 min, the PSC device harvested a high power conversion efficiency (PCE) of 8. 35% with a short-circuit current density of 15. 8 mA/cm2 , an open-circuit voltage of 0. 76 V and a fill factor of 69. 5%. It is worth mentioning that this fill factor is among the highest values in all reported BHJ devices based on PTB7 . X-ray photoelectron spectroscopy results reveal that the photo-annealing phenomenon derived from the transformation of Cs2 CO3 into Cs2 O and CO2 during photo irradiation. This evidence was further veri-fied in PSCs by employing four-week-irradiation Cs2 CO3 solution as electron extraction layer. By using the irradiated Cs2 CO3 solution, the PSC devices did not show photo-annealing phenomenon and presented almost the same device performance in comparison with those photo-annealing devices. The results indicate that this photo-annealing phenomenon is very meaningful for the reali-zation of future high-performance all-solution processed PSCs.