Editor: KONG Wenchi | Oct 15, 2021 

The recombination loss of perovskite polycrystalline film in crystal grain boundaries has not been optimized, which makes it face the bottleneck.

Perovskite monocrystal based on non-grain-boundary film have recently become a candidate material to further push solar cells to their theoretical limits. However, due to the imbalance between absorption length and carrier diffusion length, the fabrication of monocrystal film for high-efficiency perovskite solar cells has been unsatisfactory. The thickness of monocrystal is usually too large, resulting in poor efficiency of charge carrier collection.

Here, methylammonium lead iodide (MAPbI3) perovskites with controlled thickness from tens of nanometers to hundreds of nanometers have been obtained by combining the antisolvent vapor-assisted crystallization and space-confinement strategies. When perovskite monocrystal and polycrystalline film are compared, the former is found to have many excellent properties, including no grain boundary, low defect density, rarely interface defects, long carrier lifetime and high carrier mobility.

Then, solar cells based on 300 nm thick perovskite monocrystal MAPbI3 is prepared, which showed 3% enhancement in PCE compared to their polycrystalline counterparts. For thin monocrystal solar cells, the short-circuit current and PCE decreased by less than 7% after 30 days, while the short-circuit current and PCE of polycrystalline solar cells decreased by 14.3%, indicating that thin monocrystal solar cells have better resistance to air humidity. 

The reduction of crystal grain boundaries suppresses the charge recombination loss, which is the main reason for the improvement of PCE. The degradation performance of perovskite polycrystalline solar cells is more serious due to surface morphology, and polycrystalline film is rougher, the grain size is smaller, and there are more grain boundaries, which makes erosion more likely to occur. Therefore, high quality and suitable monocrystal thickness will inevitably give perovskite solar cells a more excellent PCE and stability.

This is the only way to realize its large-scale application. More importantly, thin monocrystal fabrication technique can be used for other perovskite materials, which means boosts for the performance of not only solar cells, but also photodetectors, phototransistors, and light-emitting diodes, as single crystal silicon did.

    
Contact:
Auther: KONG Wenchi 
The Guo Photonics Laboratory, State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, P R China
Changchun, Jilin 130033, China
E-mail: 1685145394@qq.com
Article links: https: //doi.org/10.1002/aenm.202000453