AUTHOR=Gupta Satyajit , Kulbak Michael , Cahen David 

TITLE=Pin-Hole-Free, Homogeneous, Pure CsPbBr3 Films on Flat Substrates by Simple Spin-Coating Modification

JOURNAL=Frontiers in Energy Research

VOLUME=8

YEAR=2020

URL=https://www.frontiersin.org/journals/energy-research/articles/10.3389/fenrg.2020.00100

DOI=10.3389/fenrg.2020.00100

ISSN=2296-598X

ABSTRACT=<p>We show a simple modification of spin-coating to obtain <italic>pinhole-free, well-covering</italic> and <italic>uniform</italic> films of an all-inorganic Pb-halide perovskite (Pb-HaP), <italic>on a flat substrate</italic> (i.e., not mesoporous) <italic>at standard temperature and pressure</italic>. In Pb-HaP-based devices the active film is generally fabricated by spin-coating. This is a challenging task for purely inorganic Pb-HaPs, as, except if nano-crystallites can be used, mostly rough and inhomogeneous thin films with poor optoelectronic quality are obtained. We describe a <italic>gas flow-assisted</italic> method to fabricate thin <italic>conformal</italic> films of phase-pure CsPbBr<sub>3</sub>. First cells made with the resulting CsPbBr<sub>3</sub>-films, yield solar conversion efficiencies up to 2.5%. Electron beam-induced current measurements of device cross-sections show uniform charge generation profiles, implying ≥ ~ 0.2 μm diffusion lengths. Non-encapsulated devices generate stable photocurrent for &gt; 1 hr under continuous illumination at maximum power in ambient.</p>