Design of Spiro-Substituted Phthalocyanine Hole-Selective Layers for Perovskite Solar Cells

The design and development of hole-selective layers remain strategic for enhancing the performance and reliability of perovskite solar cells. We introduce phthalocyanines annelated with Spiro-core substituent at the β position as a molecular semiconductor to be employed as hole-selective layers. The placement of the Spiro unit improves the molecular packing, film uniformity, and energy level alignment, enhancing the hole extraction ability of the phthalocyanine and suppressing charge recombination at the perovskite/ hole-selective layer interface. Our findings highlight the symbiotic benefits of zinc phthalocyanine with Spiro substitution to deliver a power conversion efficiency of 18.91%, approaching the performance of Spiro-OMeTAD-based devices. This work opens the path of an innovative molecular design strategy and its potential with further optimization of the newly developed Spiro substitution in zinc phthalocyanines in perovskite solar cells.