Modulate the work function of Nb2CTx MXene as the hole transport layer for perovskite solar cells

The hole transport layer (HTL) in perovskite solar cells (PVSCs) plays an important role in determining the crystallization of a perovskite film and holes transfer efficiency at the perovskite/HTL interface. Herein, the Nb2CTx Mxene with excellent photoelectric properties was prepared and utilized as the HTL in fabricating the inverted PVSCs. The work function of Nb2CTx HTL was modulated by oxygen plasma treatment through increasing the -O terminated functional groups on the Nb2CTx surface. Under this circumstance, the work function of Nb2CTx HTL was increased due to the enhanced surface dipoles, and the electrons transfer from Nb2C to the -O terminated functional groups. Furthermore, an upward band-bending occurs at the perovskite/HTL interface, which is beneficial to increase the hole transfer efficiency and reduce charge recombination. As a result, the inverted PVSCs with oxygen plasma-treated Nb2CTx HTL achieve the highest power conversion efficiency (PCE) of 20.74% and good stability. Also, the flexible and large area (0.99 cm(2)) PVSCs achieve the highest PCE of 17.26% and 17.94% by utilizing oxygen plasma-treated Nb2CTx as the HTL. Therefore, this work demonstrates that the Nb2CTx MXene has great potential application in the photovoltaic field, especially in flexible devices. Published under an exclusive license by AIP Publishing.

Automated summary

This study modulated the work function of Nb2CTx HTL through oxygen plasma treatment, leading to increased hole transfer efficiency and reduced charge recombination in inverted PVSCs.