HAT-CN-Modified\nSpiro-OMeTAD\nRealizes Efficient Perovskite\nSolar Cells

Hole\ntransport materials are essential for facilitating\nthe movement\nof holes between the perovskite layer and the electrode. Spiro-OMeTAD\n(2,2′,7,7′-tetrakis (<i>N</i>,<i>N</i>-di-<i>p</i>-methoxyphenylamine) 9,9′-spirobifluorene)\nis extensively utilized as a hole transport material among various\nalternatives. However, spiro-OMeTAD itself has a short plate with\na low hole mobility and low conductivity. We report a perovskite solar\ncell of n-i-p type with HAT-CN-modified spiro-OMeTAD as a hole transport\nlayer, while HAT-CN exhibits metalloid properties. The Fermi level\nof the hole transport layer is shifted downward, which promotes the\nmigration of holes from the perovskite layer to the spiro-OMeTAD hole\ntransport layer. The HAT-CN buffer layer reduces the roughness of\nthe spiro-OMeTAD film, thereby improving the surface contact between\nthe hole transport layer and metal electrode. The power conversion\nefficiency of the device, which was modified with a HAT-CN buffer\nlayer on the spiro-OMeTAD layer, increased from 20.45 to 21.65%. Additionally,\nthe hysteresis index decreased from 15.99 to 11.37% and the device\nstability improved. This strategy effectively enhances both the charge\ncarrier mobility and hydrophobicity of the spiro-OMeTAD layer, thereby\nfacilitating the achievement of efficient and stable perovskite solar\ncells.