Efficient planar perovskite solar cells with low-temperature atomic layer deposited TiO2 electron transport layer and interfacial modifier

Perovskite solar cells (PSCs) have attracted increasing attentions for their outstanding efficiency and simple fabrication process. However, the commonly used typical titanium dioxide (TiO₂) electron transport layer (ETL) requires a high-temperature treatment to crystallize. In this work, the low-temperature (150 °C) atomic layer deposition (ALD) processed TiO₂ ETL, and the SnO₂/PCBM double interfacial modifier have been adopted to fabricate the high performance PSCs of ITO/ALD-TiO₂/SnO₂/PC₆₁BM/MA_0.7FA_0.3PbI_(3-x)Cl_(x)/Spiro-OMeTAD/Ag. The measurement results show that the PSCs with ALD-TiO₂ ETL obtain the higher champion PCE of 19.45% than that of PSC with solution-TiO₂ ETLs (PCE = 18.64%), along with the obviously enhanced FF and V_OC, as well as the better light stability and repeatability. And the transient photocurrent and photovoltage results demonstrate that the performance improvement origins from the enhanced charge transport and suppressed charge recombination. Therefore, the low-temperature ALD-TiO₂ ETL with suitable modification is a promising strategy to fabricate efficient PSCs and flexible devices.