New ferrocenyl-containing organic hole-transporting materials for perovskite solar cells in regular (n-i-p) and inverted (p-i-n) architectures

Three triphenylamine derivatives containing ferrocenyl groups (JW6, JW7 and JW8) were synthesized by facile syntheses. Their HOMO levels match the valence band energy of CH(3)NH(3)PbI(3). The introduction of ferrocenyl was aimed to obtain hole transporting materials with high mobility for perovskite solar cells. JW7 shows higher hole mobility (4.2 × 10(−4) cm(2) V(−1) s(−1)) than JW6 (1.3 × 10(−4) cm(2) V(−1) s(−1)) and JW8 (1.5 × 10(−4) cm(2) V(−1) s(−1)). Their film-forming properties are affected by their molecule structures. The methoxyl and N,N-dimethyl terminal substituents of JW7 and JW8 are beneficial for having better solubility than JW6. The regular mesoporous TiO(2)-based perovskite solar cells (n-i-p) and the inverted planar heterojunction perovskite solar cells (p-i-n) fabricated using JW7 show the highest power conversion efficiency of 9.36% and 11.43% under 100 mW cm(−2) AM1.5G solar illumination. For p-i-n cells, the standard HTM PEDOT-based cell reaches an efficiency of 12.86% under the same conditions.