Impact of MAPbBr3 Additives on Crystallinity and Charge Carrier Dynamics of Mixed Perovskite Films

Organic-metal halide perovskite is one of the most promising candidates for the next generation solar cell material owing to its superior photo-electric properties and relatively simple fabrication process. In particular, FAPbI
3
turned out to be very suitable for efficient solar cell due to its low band gap energy
$(\sim 1.5\ \text{eV})$
. However, FAPbI
3
shows the crystal phase instability between unfavourable yellow trigonal δ-phase and perovskite-type black cubic a-phase at room temperature. To stabilize it, various additives such as MACl, Cs and MAPbBr
3
have been proposed and studied. Recently, there was a report that 0.8 mol% of MAPbBr
3
additive stabilizes the crystal phase of FAPbI
3
, and subsequently, a photo conversion efficieny (PCE) of 25.2% was achieved [1]. However, the influence of MAPbBr
3
additives on charge carrier dynamics and its correlation with crystallinity is still unrevealed.