p-Type Dopants As Dual Function Interfacial Layer for Efficient and Stable Tin Perovskite Solar Cells

Interfacial engineering plays a key role for the stability and efficiency of perovskite photovoltaics, especially for the tin perovskite solar cells (TPSCs). Herein, a simple and effective interfacial layer approach to modify the heterointerface between hole transport layer (HTL) and perovskite active layer is reported. By the deposition of a p-type dopant, tetrafluoro-tetracyanoquinodimethane (F4TCNQ) onto the commonly used poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) HTL, a favorable energy level alignment with the mixedcation tin perovskite is obtained. Moreover, the F4TCNQ interfacial layer introduces a passivated contact and suppressed trap density at the HTL/ perovskite interface through halogen bonding. As a result, the optimized TPSC yields an improved efficiency of 8.11% as compared with 6.41% of the reference device. Meanwhile, the stability of the TPSC is also improved due to the hydrophobicity of the F4TCNQ interfacial layer. This work demonstrates that the incorporation of an interfacial layer at the HTL/perovskite interface is a feasible approach to boost the efficiency and stability of inverted TPSC.

Automated summary

The research successfully modified the heterointerface between the perovskite active layer and the hole transport layer (HTL) by depositing a p-type dopant, tetrafluoro-tetracyanoquinodimethane (F4TCNQ), on the commonly used poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) HTL. The interfacial layer introduced a passivated contact and suppressed trap density at the HTL/perovskite interface through halogen bonding, leading to an improved efficiency and stability of the inverted tin perovskite solar cells (TPSC).