Chemical Polishing of Perovskite Surface Enhances Photovoltaic Performances

Abstract

The benefits of excess PbI 2 on perovskite crystal nucleation and growth are countered by the photoinstability of interfacial PbI 2 in perovskite solar cells (PSCs). Here we report a simple chemical polishing strategy to rip PbI 2 crystals off the perovskite surface to decouple these two opposing effects. The chemical polishing results in a favorable perovskite surface exhibiting enhanced luminescence, prolonged carrier lifetimes, suppressed ion migration, and better energy level alignment. These desired benefits translate into increased photovoltages and fill factors, leading to high-performance mesostructured formamidinium lead iodide-based PSCs with a champion efficiency of 24.50%. As the interfacial ion migration paths and photodegradation triggers, dominated by PbI 2 crystals, were eliminated, the hysteresis of the PSCs was suppressed and the device stability under illumination or humidity stress was significantly improved. Moreover, this new surface polishing strategy can be universally applicable to other typical perovskite compositions.

Surface Re-Engineering of Perovskites with Buckybowls to Boost the Inverted-Type Photovoltaics

“…More detailed illustrations of the synthetic routes from corannulenes to ACIs can be found in Schemes S1 and S2 in the Supporting Information. For the sake of comparison, three other π-conjugated ionic compounds were also selected for PSC fabrication, including two commercially available phenyl-based ammonium salts (phenylammonium iodide (PhAI) and phenmethylammonium iodide (PhMAI)) , and a home-synthesized fullerene-based ammonium salt (FuAI) based on our previous works (Figure S1). , As displayed in Figures S2–S5, all synthesized corannulene-derived compounds in this work were unambiguously characterized by 1 H NMR spectroscopy, 13 C NMR spectroscopy, and mass spectrometry.…”

Construction of Efficient and Stable FAPbI3 Perovskite Solar Cells through Bifunctional Ionic Liquid‐Assisted Crystallization and Defect Passivation

“…One effective strategy is incorporation of smaller‐sized cations and anion, such as Cs + , MA + , and Br − , to stabilize α‐FAPbI 3 by regulating the Goldschmidt tolerance factor of perovskite. [ 20,29–31 ] However, the introduction of Cs + , MA + , and Br − comes at the cost of a blueshifted absorption spectrum, limiting the further enhancement of PCE. Furthermore, it was also found that Br − can cause phase segregation under long‐term illumination.…”

Patterned 2D Perovskite Film with a Preferably Orientated 3D-Like Phase for Efficient Perovskite Solar Cells

“…With the application of temperature, negligible PbI 2 appeared, which according to previous reports can act as an additional additive to passivate defects. 44,45 Besides, the effect of the imprinting pressure on the crystallinity of the perovskite layers was also verified (Figure S14). It was obviously that the crystallinity and orientation increased with the pressure.…”