Cu(II) and Ni(II) Phthalocyanine-Based Hole-Transporting Materials for Stable Perovskite Solar Cells with Efficiencies Reaching 20.0%

Herein, Cu(II)Pcs and Ni(II)Pcs peripherally tetra-functionalized with 5-hexylthiophene (HT), 5-hexyl-2,2 '-bithiophene (HBT), and tertbutyl groups (TB) are readily synthesized and employed as hole-transporting materials (HTMs) in mixed-ion perovskite ([FAPbI3]0.85[MAPbBr3]0.15) solar cells, achieving power conversion efficiencies (PCEs) up to 20.0%. Remarkably, both the peripheral functionalization and the central metal are found to play a role in the performance. Through a combination of experimental and theoretical techniques, it is found that the simplest HTM, TB-CuPc, is the best-performing HTM primarily due to its higher hole mobility and a more appropriate highest-occupied molecular orbital, whose enables efficient hole extraction without open-circuit voltage (Voc)losses. This derivative leads to PCEs of 19.96%, which are among the highest values for Pc-based HTMs. Importantly, devices incorporating these HTMs present significantly higher stability compared to those based on spiro-OMeTAD. The results here presented pave the way for more realistic, efficient, and inexpensive photovoltaic devices using phthalocyanine derivatives. Herein, Cu(II)Pcs and Ni(II)Pcs peripherally tetra-functionalized with 5-hexylthiophene (HT), 5-hexyl-2,2'-bithiophene (HBT), and tertbutyl groups (TB) are readily synthesized and employed as hole-transporting materials in mixed-ion perovskite ([FAPbI3]0.85[MAPbBr3]0.15) solar cells, achieving power conversion efficiencies up to 20.0%.image (c) 2024 WILEY-VCH GmbH