Performance enhancement of perovskite solar cells with Mg-doped TiO_2 compact film as the hole-blocking layer

摘要

In this letter, we report perovskite solar cells with thin dense Mg-doped TiO_2 as hole-blocking layers (HBLs), which outperform cells using TiO_2 HBLs in several ways: higher open-circuit voltage (V_(oc)) (1.08 V), power conversion efficiency (12.28%), short-circuit current, and fill factor. These properties improvements are attributed to the better properties of Mg-modulated TiO_2 as compared to TiO_2 such as better optical transmission properties, upshifted conduction band minimum (CBM) and downshifted valence band maximum (VBM), better hole-blocking effect, and higher electron life time. The higher-lying CBM due to the modulation with wider band gap MgO and the formation of magnesium oxide and magnesium hydroxides together resulted in an increment of V_(oc). In addition, the Mg-modulated TiO_2 with lower VBM played a better role in the hole-blocking. The HBL with modulated band position provided better electron transport and hole blocking effects within the device.