In Situ Thermal Cross-Linking of 9,9′-Spirobifluorene-Based Hole-Transporting Layer for Perovskite Solar Cells

High Resolution Image Download MS PowerPoint Slide A novel 9,9′-spirobifluorene derivative bearing thermally cross-linkable vinyl groups ( V1382 ) was developed as a hole-transporting material for perovskite solar cells (PSCs). After thermal cross-linking, a smooth and solvent-resistant three-dimensional (3D) polymeric network is formed such that orthogonal solvents are no longer needed to process subsequent layers. Copolymerizing V1382 with 4,4′-thiobisbenzenethiol (dithiol) lowers the cross-linking temperature to 103 °C via the facile thiol–ene “click” reaction. The effectiveness of the cross-linked V1382 /dithiol was demonstrated both as a hole-transporting material in p–i–n and as an interlayer between the perovskite and the hole-transporting layer in n–i–p PSC devices. Both devices exhibit better power conversion efficiencies and operational stability than devices using conventional PTAA or Spiro-OMeTAD hole-transporting materials.