Highly Stable Strontium Fluoride as a Thickness Tolerant
Electron‐Selective Contact for Dopant‐Free Silicon Solar Cells
Abstract
Commercialized passivated emitter rear cell (PERC) silicon solar cells
feature direct contact of metal with silicon, which leads to severe
recombination loss and low open circuit voltage
(Voc). To overcome the loss, the authors
demonstrate a highly stable and thickness-tolerant dopant-free
electron-selective contact consisting of a strontium fluoride/aluminium
(SrF2/Al) stack. The inserting SrF2
layer can mitigate the Fermi-level pinning effect between the silicon
substrate and the Al electrode. Besides, a relatively low Ohmic contact
resistivity of 2 mΩ·cm2 on lightly doped n-type c-Si
can be achieved when using 4 nm of SrF2. Moreover, the
formed contact within 9 nm SrF2 is stable for over 5000
hours in the air without encapsulation. Solar cells with this novel
dopant-free electron-selective contact reach a power conversion
efficiency (PCE) of 21.56%. The promising results and its stable
nature, indicate its potential to act as efficient electron-selective
contact for various optoelectronic devices.