Soluble hexamethyl-substituted subphthalocyanine as a dopant-free hole transport material for planar perovskite solar cells

Boron subphthalocyanine (SubPc) has special physical and chemical properties, originating from its non-centrosymmetric, near-planar taper structure and large conjugated system; it can act as an alternative to the small molecule hole-transporting material 2,2’,7,7’-tetrakis-(N,N-di-p-methoxyphenylamine)-9,9’-spirobifluorene in perovskite solar cells. To achieve a higher solubility in common organic solvents and a more suitable highest occupied molecular orbital (HOMO) energy level that aligns with the valence band of the perovskite material, a SubPc molecule with a hexamethyl substitution at its peripheral position (Me6-SubPc) was successfully designed and synthesized in a one-step method. Completely solution processed perovskite solar cells were fabricated with only a small hysteresis, a power conversion efficiency (PCE) of 6.96% and Voc of 0.986 V.

硼亚酞菁（Boron subphthalocyanine, SubPc）具有独特的物理与化学性质，这源于其非中心对称的近平面锥形结构与大共轭体系；其可作为钙钛矿太阳能电池中小分子空穴传输材料2,2',7,7'-四(N,N-二对甲氧基苯基胺基)-9,9'-螺双芴的替代材料。为使其在常见有机溶剂中具备更高溶解度，并获得与钙钛矿材料价带能级匹配的更适宜的最高占据分子轨道（HOMO）能级，研究人员通过一步法成功设计并合成了外围位点带有六甲基取代的SubPc分子（Me6-SubPc）。采用该材料制备的全溶液加工钙钛矿太阳能电池仅表现出较小的迟滞效应，光电转换效率（PCE）达6.96%，开路电压（Voc）为0.986 V。