The electron transport layer(ETL) plays an important role in planar heterojunction perovskite solar cell(PSCs),by affecting the light-harvesting, electron injection and transportation processes, and especially the crystallization of perovskite absorber. In this work, we utilized a commercial TKD-TiO_2 nanoparticle with a small diameter of 6 nm for the first time to prepare a compact ETL by spin coating. The packing of small-size particles endowed TKD-TiO_2 ETL an appropriate surface-wettability, which is beneficial to the crystallization of perovskite deposited via solution-processed method. The uniform and high-transmittance TKD-TiO_2 films were successfully incorporated into PSCs as ETLs. Further careful optimization of ETL thickness gave birth to a highest power conversion efficiency of 11.0%, which was much higher than that of PSC using an ETL with the same thickness made by spray pyrolysis. This TKD-TiO_2 provided a universal solar material suitable for the further large-scale production of PSCs. The excellent morphology and the convenient preparation method of TKD-TiO_2 film gave it an extensive application in photovoltaic devices. The electron transport layer (ETL) plays an important role in planar heterojunction perovskite solar cells (PSCs), by affecting the light-harvesting, electron injection and transportation processes, and especially the crystallization of perovskite absorber. In this work, we utilized a commercial TKD-TiO 2 nanoparticle with a small diameter of 6 nm for the first time to prepare a compact ETL by spin coating. The packing of small-size particles endowed TKD-TiO 2 ETL an appropriate surface-wettability, which is beneficial to the crystallization of perovskite The uniform and high-transmittance TKD-TiO 2 films were successfully incorporated into PSCs as ETLs. Further careful optimization of ETL thickness gave birth to the highest power conversion efficiency of 11.0%, which was much higher than that of PSC using an ETL with the same thickness made by spray pyrolysis. This TKD-TiO 2 provided a universal solar material suitable for the further large-scale pro duction of PSCs. The excellent morphology and the convenient preparation method of TKD-TiO_2 film gave it an extensive application in photovoltaic devices.