Highly reproducible vapor deposition technique, device physics and structural instability of perovskite solar cells

Thermally Stable, Efficient, Vapor Deposited Inorganic Perovskite Solar Cells

“…JV curves of MAPbI3 solar cells before and after thermal degradation at 110°C for 1 hours[18] Similarly, another commonly used perovskite material, FAPbI3, undergoes thermal degradation at slightly higher temperatures of 125°C over 24 hours [Fig. 4.6][19].…”

Vapor grown Perovskite solar cells

“…The ions accumulating at the interface, reduces the internal electric field ( dependent of field) and built-in-voltage, thereby reducing the Open circuit voltage and carrier collection. Carrier collection, because perovskite is a field controlled device as experimentally shown by Dalal et al [171]. In addition, there is a decrease in collected carriers due to the increased recombination in the bulk owing to the broken bonds that arises owing to the ions migrating from the bulk to the interface, thus increasing 0 and reducing the .…”

“…However, for material like perovskite whose carrier collection is field assisted [171], the thickness of film is critical, as it determines carrier collection. Since, QCM doesn't work, an alternative approach is doing calibration runs, knowing rate and depositing for 300nm.…”

“…As mentioned in the fabrication section, the optimal thickness is in the ~350nm range. In our previous work, we published that perovskite is a field controlled device [171], so if thickness is greater than the range of the field, carrier collection would decrease. To show this, we made a ~500nm perovskite device and measured the QE for the same with and without a bias.…”

Inorganic metal halide perovskite solar cell devices

“…Figure 3.4 is showing the XRD data for MAI perovskite film before and after annealing at 100°C for 24 hours. After the annealing, an obvious peak around 2θ = 12°popped up, which is the PbI 2 peak [36]. With other small peaks showing in XRD after the anneal and intensity change for those major big peaks, it is clear that MAI perovskite was degraded and decomposed.…”