Fabrication of Compact Films Butyl Ammonium Chloride Doping into Cs3Bi2I9: Improved Film Morphology

Abstract

Albeit the iconic lead-based perovskites solar cell has summited power
conversion efficiency (PCE) of 23%. Lead toxicity remains a glitch for its
commercialization. To replace the toxic lead, numerous alternatives have been
introduced. Out of many, bismuth (Bi) was introduced as a stable alternative
with isoelectronic properties to the conventional lead in perovskites (PVKs)
framework. However, Bi-based PVKs also encountered several problems; for
example, poor film morphology and crystallinity. The crystallization of Bibased PVKs is abrupt and does not form any intermediate solvated phases,
leading toward isolated crystals formation instead of uniform pinholes-free
films. Hence, it is challenging to fabricate compact thin films of Bi-based PVKs.
Herein, we attempted to fabricate compact and pinholes-free Bi-based PVKs
film by incorporating butyl ammonium chloride (BACl) into the precursor
solution of the Bi-based PVKs. Preliminary results indicate that the doping of
BACl not only caused the improvement in the film morphology but also
improved the crystallinity of the film. We believe that these results could be
helpful in the material development of the Bi-based PVKs and their utilization
in optoelectronic devices.