Precise control of PbI2 excess into grain boundary for efficacious charge extraction in off-stoichiometric perovskite solar cells

Small grains as recombination hot spots in perovskite solar cells

“…Indeed, it has been shown that the rate of ionic transport is influenced by the relative orientation of the grains, 28 suggesting that grain orientation may also influence other properties. Grain boundaries may also exhibit other phenomena, such as complexation, 29 chemical excess of either PbI 2 30 or organic halides, 31 or the presence of amorphous phases, 32 especially in the case of non-stoichiometric compositions; however, recent work by Rothmann et al has shown that grain boundaries in high-quality polycrystalline perovskite films are atomically clean. 33 The situation may be further complicated by the fact that not all crystallographic grains are resolved by commonly used microscopic methods such as scanning electron microscopy (SEM) or atomic force microscopy (AFM).…”

Efficient fully blade-coated perovskite solar cells in air with nanometer-thick bathocuproine buffer layer

“…PSC with an excess of PbI2 shown faster degradation compare to those without for the well-known Ag/I interaction. Also, excess of PbI2 could be controlled by tuning the deposition parameters during coating or even in thermal annealing of films [42]. SEM and Raman analysis were carried on to better understand the perovskite growth.…”

Insights into Ultrafast Carrier Dynamics in Perovskite Thin Films and Solar Cells

“…The photogenerated carriers are in an unbalanced state and need to undergo a series of evolutions to reach equilibrium and stability again. 29,34,35 Therefore, a microscopic understanding of these dynamic processes is necessary to boost the performance of PSCs further. Here, the recent advances of the ultrafast dynamics of photoinduced charge carriers in perovskite thin films and PSCs are reviewed.…”

“…This bimolecular constant is about 4 orders of magnitude under the Langevin rates, that is k 2 ≈ 10 –10 cm 3 s –1 . , When an optical source with photon energy greater than the bandgap width excites perovskite, the electrons in VB will transfer to the conduction band (CB), while holes will be left in VB. The photogenerated carriers are in an unbalanced state and need to undergo a series of evolutions to reach equilibrium and stability again. ,, …”