Chinese researchers fabricated new perovskite solar cells (PSCs) with high power conversion efficiency of 18.1% by insertingTitanium (Ti) cathode layer.
Two different device configurations including n-i-p and p-i-n have been adopted for fabricating PSCs. As organic electron transport layers (ETLs), fullerene and its derivatives (C60 and PCBM) play an important role in efficient PSCs with p-i-n structure (ITO/Hole transport layers/perovskite/ETLs/Cathode).
However, the cathode metal atoms diffused through the organic ETLs to the perovskite layer, causing degradation of PSCs. Besides, the instability and high-cost of organic ETLs were limitation for the commercialization of PSCs.
Considering these problems, the research team led by Dr. LI Xinhua at Institute of Solid State Physics, Hefei Institutes of Physical Science, developed the ultra-thin Ti cathode interlayer to replace organic ETLs for fabricating efficient and low-cost PSCs.
The Ti-N bond between MAPbI3 and Ti was able to passivate the surface traps and suppress surface decomposition of the MAPbI3 film.
And owing to low diffusion coefficient of Ti, the diffusion of Au was suppressed in the PSCs with Ti interlayer.
Furthermore, after incorporation of Ti interlayer, the PCE increases substantially for both Au and Cu electrodes, although the work function of Cu (-4.3eV) and Au (-5.1eV) were very different.
The findings have been published online in Solar RRL.
This research was supported by National Natural Science Foundation of China, the Joint Funds of the National Natural Science Foundation of China.
Link to the paper: https://onlinelibrary.wiley.com/doi/abs/10.1002/solr.201800167