2-Aminoethanethiol Hydroiodate Additives Induced Phase Stability Improvement of CsPbI₃ Films for Use in Inorganic Perovskite Solar Cells

This study investigates the role of 2-aminoethanethiol hydroiodate (2-AET·HI) additives in enhancing the phase stability and photovoltaic performance of CsPbI₃ films for inorganic perovskite solar cells. The incorporation of 2-AET·HI into the precursor solution results in a more uniform and compact film morphology. X-ray diffraction (XRD) analysis reveals that the 2-AET·HI-treated CsPbI₃ films retain their black α-phase, even after 300 h at 25% RH and ∼25 °C, whereas the control samples show a rapid transition to the nonphotoactive δ-phase. This improvement in phase stability is reflected in the enhanced photovoltaic performance, with the 2-AET·HI-modified devices exhibiting a power conversion efficiency (PCE) of 16.7%, compared to 15.4% for the control devices. Furthermore, the 2-AET·HI-modified devices display superior long-term stability, retaining 83% of their initial PCE after 192 h in ambient conditions, in stark contrast to the unmodified devices, which degrade rapidly.