High-quality CH3NH3PbI3 thin films were fabricated using a one-step spin-coating method.
Iodobenzene can be substituted for toluene as a more efficient nonpolar antisolvent.
The grain size in CH3NH3PbI3 thin films was increased from 285 nm to 376 nm.
The JSC (PCE) was improved from 18.8 mA/cm2 (12.3%) to 21.7 mA/cm2 (13.7%).