Coagulated SnO₂ Colloids for High‐Performance Planar Perovskite Solar Cells with Negligible Hysteresis and Improved Stability

Abstract

Organic–inorganic perovskite solar cells with a planar architecture have attracted much attention due to the simple structure and easy fabrication. However, the power conversion efficiency and hysteresis behavior need to be improved for planar‐type devices where the electron transport layer is vital. SnO2 is a promising alternative for TiO2 as the electron transport layer owing to the high charge mobility and chemical stability, but the hysteresis issue can still remain despite the use of SnO2. Now, a facile and effective method is presented to simultaneously tune the electronic property of SnO2 and passivate the defects at the interface between the perovskite and SnO2. The perovskite solar cells with ammonium chloride induced coagulated SnO2 colloids exhibit a power conversion efficiency of 21.38 % with negligible hysteresis, compared to 18.71 % with obvious hysteresis for the reference device. The device stability can also be significantly improved.

Recent Progresses on Defect Passivation toward Efficient Perovskite Solar Cells

“…[43,44] Some new tools, like electron-beam-induced current (EBIC), [45] secondary ion mass spectrometry (SIMS) and scanning tunneling microscope (STM) [46,47] are utilized to explore the location and nature of defects, supplemented by density functional theory (DFT) calculation. [48,49] We fully believe that a better understanding of the changes in the nature of defects in passivation will be obtained with the help of new characterizations, thereby further optimizing the passivation strategy.…”

“…In addition, the introduction of chloride ions in SnO 2 by doping ammonium chloride in the precursor solution can also effectively eliminate hysteresis. According to the DFT calculation results, Cl − and NH 4 + ions make the system more stable at the interface, [49] because it is more compatible with the crystal structure of SnO 2 than MA + and I − in perovskite. The formation energy of the Pb-I antiside defect is also higher after the introduction of ammonium chloride.…”

“…Reproduced with permission. [49] Copyright 2019, Wiley-VCH www.advancedsciencenews.com Figure 11e), more matched energy bands and increased electron mobility allowed the device to achieve a PCE of 21.38% with negligible hysteresis. Additionally, Liang et al thought that NH 4…”

“…Characterization techniques like photo luminescence (PL), time‐correlated single photon counting (TCSPC), Kelvin probe force microscopy (KPFM) and thermal admittance spectroscopy (TAS) are often used to delineate the effect of defect passivation . Some new tools, like electron‐beam‐induced current (EBIC), secondary ion mass spectrometry (SIMS) and scanning tunneling microscope (STM) are utilized to explore the location and nature of defects, supplemented by density functional theory (DFT) calculation . We fully believe that a better understanding of the changes in the nature of defects in passivation will be obtained with the help of new characterizations, thereby further optimizing the passivation strategy.…”

“…e) V OC versus light intensity for the PSCs using SnO 2 and NH 4 Cl-SnO 2 . Reproduced with permission [49]. Copyright 2019, Wiley-VCH…”