Porous Organic Cage Induced Spontaneous Restructuring of Buried Interface Toward High‐Performance Perovskite Photovoltaic

Abstract

In perovskite solar cells (PSCs), the buried interface containing high concentrations of defects is critical for efficient charge extraction toward high-performance device. Herein, porous organic cage (POC) is introduced between tin dioxide and perovskite to spontaneously reconstitute the buried interface. Through the chemical linkage formed by polydentate chelation of POC with SnO 2 and perovskite, the buried interface achieves greatly reduced defect density and enhanced carrier extraction. More importantly, it is found that iodide ions in aged devices to migrate down to the electron transport layer and even invade the ITO electrode, changing the work function of ITO. This detrimental effect can be well resolved by POC since the host-guest interaction of POC can effectively suppress the iodide ions trying to migrate downward. As a result, the PSC fabricated by POC-restructured strategy yields a superior PCE of 24.13%. Moreover, the unencapsulated PSCs exhibit conspicuous improved long-term stability and retain 93% of its initial efficiency after 5000 h in ambient condition.

First-Principles Study of Group VA Monolayer Passivators for Perovskite Solar Cells

“…21−25 For example, Dong et al and Gao et al have employed chlorobenzenesulfonic potassium salts and porous organic cages to passivate the buried tin oxide (SnO 2 )/ perovskite interface, which results in better energy alignment, reduced trap states, and improved stability. 24,26 Similarly, Xu et al reported the successful use of daminozide as an interlayer to modify interface energetics and passivate defects at the interface as well as in perovskite bulk. 22 Although high performance of PSCs has been achieved through the trap-state passivation, the mechanism is still complicated and excellent trap-state passivators are insufficient, which require further exploration and study.…”

“…In addition, PSCs are suffering from significant non-radiative recombination losses originated from defect states of perovskites. Until now, numerous passivating strategies including solvent, composition, and interfacial engineering have been developed to enhance both efficiency and long-term stability. − Specially, the buried interface between the perovskite layer and the underlying transport layer has been vastly investigated to minimize trap states and recombination losses as well as facilitate carrier extraction. − For example, Dong et al and Gao et al have employed chlorobenzenesulfonic potassium salts and porous organic cages to passivate the buried tin oxide (SnO 2 )/perovskite interface, which results in better energy alignment, reduced trap states, and improved stability. , Similarly, Xu et al reported the successful use of daminozide as an interlayer to modify interface energetics and passivate defects at the interface as well as in perovskite bulk . Although high performance of PSCs has been achieved through the trap-state passivation, the mechanism is still complicated and excellent trap-state passivators are insufficient, which require further exploration and study.…”

Facet Engineering: A Promising Pathway toward Highly Efficient and Stable Perovskite Photovoltaics

“…The compact polycrystalline film formed by the FAPbI 3 component with better light absorption capacity and chemical stability stood out in 2015 . In the third period, which is still ongoing, the efforts have been mainly focused on passivation of defects at grain boundaries, upper surfaces, and buried interfaces of FAPbI 3 -based films, plus modulation of the transport materials. , …”

Exploring charge behavior at the terminal surface and charge separation interface of organo-lead perovskite using in situ surface photovoltage spectroscopy

“…3 However, a thorough investigation into the contribution of surface charge transfer to photovoltaic action and photovoltage is still lacking. 4,5 The lattice dynamics and electronic states of the free surface terminal and hetero-interface of perovskite have been the subject of extensive research in recent years. [6][7][8] Surface-localized electronic states can occur when the periodic structure of a perovskite terminates at its free surface.…”

“…3 However, a thorough investigation into the contribution of surface charge transfer to photovoltaic action and photovoltage is still lacking. 4,5…”