Universal Passivation Strategy for the Hole Transport Layer/Perovskite Interface via an Alkali Treatment for High‐Efficiency Perovskite Solar Cells

Abstract

A passivation strategy for the perovskite/HTL interface is presented based on potassium acetate (K‐Ac). Since K‐Ac is soluble in both polar and nonpolar solvent, deposition of K‐Ac on top and bottom of perovskite is possible. With this advantage, the universality of potassium interfacial passivation at the HTL/perovskite interface applied to various configurations with various ranges of perovskite bandgap is reported. Regarding the p–i–n configuration, various materials characterizations reveal that a potassium passivation layer underneath perovskite modifies perovskite orientations, resulting in better charge transport and film properties. Furthermore, the potassium passivation layer shifts the valence band position of the HTL upward, which results in a better extraction of charges (holes) across the HTL/perovskite interface, thus improving the short‐circuit current density (Jsc). The modification of the band alignment at the HTL/perovskite by the potassium interfacial passivation layer is confirmed in n–i–p devices with both WBG and CBG perovskites. Compared to reference solar cells without a passivation layer, an increase in Jsc of approximately 1 mA cm−2 is observed in all cases, resulting in power conversion efficiencies of 19.42%, 20.06%, and 21.57% for WBG p–i–n, CBG p–i–n and n–i–p solar cells, respectively, demonstrating the wide applicability of the passivation strategy.

Recent advances in the interfacial engineering of organic–inorganic hybrid perovskite solar cells: a materials perspective

“…A passivation strategy for the perovskite/HTL interface using potassium acetate (K-Ac) was presented. 140 The unique K-Ac can be soluble in a wide range of solvents, enabling it to be used as a bottom and top interface layer. In n-i-p devices, this interfacial passivation layer improved the energy-band alignment of the perovskite/HTL interface, ultimately achieving a superior efficiency of 21.57% compared with the control devices.…”

Selective reactivity-assisted sacrificial additive coating for surface passivation of wide bandgap perovskite solar cells with cesium tetrafluoroborate

“…[21][22][23] The perovskite surface has been passivated primarily by depositing large organic cations via spin coating. 24 For example, Jiang et al passivated the surface defects of a FA 0.92 -MA 0.08 PbI 3 (FA: formamidinium, MA: methylammonium) lm by post-treatment with PEAI. 25 Gharibzadeh et al also improved the V OC of WBG PSCs utilizing 2D/3D perovskite heterostructures by spin coating n-BABr.…”

Interfacial and Doping Synergistic Effect of Versatile Potassium Acetate toward Efficient CsPbI2Br Perovskite Solar Cells

“…used alkali hydroxides CBL to modify the SnO 2 /CsPbI 2 Br interface in light of the defect density in SnO 2 caused by the uncoordinated Sn 4+ . , Concurrently, the novel functionalized transporting layers such as poly-TPD hole transporting layer or ZnO@SnO 2 electron transporting layer (ETL) were developed to promote carrier transport. , Potassium acetate (KAc) displays exceptional solubility across a broad range of solvents, including highly polar solvents like H 2 O or N , N -dimethylformamide (DMF), and less polar solvents such as ethanol or isopropanol. This characteristic renders KAc for use as an interfacial layer or an additive in the enhancement of the photovoltaic performance of organic–inorganic hybrid PSCs. − To our knowledge, most of these materials play only one role, rather than multiple roles like both interfacial modifier and additive. The versatile materials merit study since they diminish the interfacial and bulk defects in PSCs and align the energy levels simultaneously.…”