HAT-CN-Modified Spiro-OMeTAD Realizes Efficient Perovskite Solar Cells

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