Correlation between Interfacial Structures and Device Performance: The Double-Edged Sword Effect of Lead Iodide in Perovskite Solar Cells.

The interfacial electronic structure of perovskite layers and transport layers is critical for the performance and stability of perovskite solar cells (PSCs). The device performance of PSCs can generally be improved by adding a slight excess of lead iodide (PbI ) to the precursor solution. However, its underlying working mechanism is controversial.

In Situ Surface Fluorination of TiO Nanocrystals Reinforces Interface Binding of Perovskite Layer for Highly Efficient Solar Cells with Dramatically Enhanced Ultraviolet-Light Stability.

Low-temperature solution-processed TiO nanocrystals (LT-TiO) have been extensively applied as electron transport layer (ETL) of perovskite solar cells (PSCs). However, the low electron mobility, high density of electronic trap states, and considerable photocatalytic activity of TiO result in undesirable charge recombination at the ETL/perovskite interface and notorious instability of PSCs under ultraviolet (UV) light. Herein, LT-TiO nanocrystals are in situ fluorinated via a simple nonhydrolytic method, affording formation of Ti─F bonds, and consequently increase electron mobility, decrease density of electronic trap states, and inhibit photocatalytic activity.

Fast Wetting of a Fullerene Capping Layer Improves the Efficiency and Scalability of Perovskite Solar Cells.

Fullerene derivatives, especially [6,6]-phenyl-C-butyric acid methyl ester (PCBM), have been widely applied as electron transport layers of inverted planar heterojunction perovskite solar cells (PSCs). However, the solution-processed PCBM capping layer suffers from limited surface wetting which hinders the improvement in efficiency and scalability of PSCs. Herein, we develop a facile hybrid solvent strategy that enables very fast wetting of the PCBM capping layer atop of the perovskite surface, leading to an improved interfacial contact and electron transport.

Potassium salt promoted regioselective three-component coupling synthesis of 1,4-asymmetrical [60]fullerene bisadducts with superior electron transport properties.

An efficient one-pot three-component domino coupling reaction of phenols, C60, and bromoalkanes was developed, resulting in the highly regioselective synthesis of 1,4-asymmetrical C60 bisadducts. The reaction utilizes KOtBu as a promoter and likely proceeds by an oxyanion/carbanion rearrangement/nucleophilic addition cascade. This new methodology is particularly effective for the synthesis of 1,4-asymmetrical C60 electron transport materials.