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Room‐temperature‐processed TiO2 (R‐Lt‐TiO2) electron transporting layers (ETLs) possess low conductivity and connectivity, resulting in poor photovoltaic performance. Herein, an ethanol (EtOH)‐soluble, highly conducting fullerene derivative, C60RT6, was used as an additive for Lt‐TiO2 ETLs. Room‐temperature processed nanocomposite ETL (R‐Fu/Lt‐TiO2) is prepared simply by spin coating a C60RT6 and G‐TiO2 NPs (TiO2 nanoparticle prepared by grinding the bulk TiO2 powder) mixture. R‐Fu/Lt‐TiO2 has better aligned with the frontier orbitals of the FAxMA1−xPbI3, better continuity, conductivity, flatness, and higher surface hydrophilicity compared to Lt‐TiO2 ETL. Perovskite films spin coated on R‐Fu/Lt‐TiO2 ETLs also have slightly larger grains and thickness compared to those deposited on Lt‐TiO2. Perovskite solar cells (PSCs) based on a R‐Fu/Lt‐TiO2 ETL possess higher power conversion efficiency (PCE, up to 20% on glass substrate), less (negligible) current hysteresis, and better long‐term stability compared to those using R‐Lt‐TiO2 as an ETL. The flexible PSC (used indium tin oxide/polyethylene terephthalate (ITO/PET) as a substrate) with a R‐Fu/Lt‐TiO2 ETL achieves a PCE of 18.06% and retains 90% of the initial PCE after 500 bending cycles with a bending radius of 6 mm. The PCE of the flexible cell with a Lt‐TiO2 ETL is only 8.2%, and loses 60% of the initial value after 500 bending cycles. [ABSTRACT FROM AUTHOR]

Sputtering made ZnO thin film was used as an electron-transport layer in a regular planar perovskite solar cell based on high quality CH3NH3PbI3 absorber prepared with a two-step spin-coating. An efficiency up to 15.9% under AM 1.5G irradiation is achieved for the cell based on ZnO film fabricated under Ar working gas. The atmosphere of the sputtering chamber can tune the surface electronic properties (band structure) of the resulting ZnO thin film and therefore the photovoltaic performance of the corresponding perovskite solar cell. Precise surface engineering of ZnO thin film was found to be one of the key steps to fabricate ZnO based regular planar perovskite solar cell with high power conversion efficiency. Sputtering method is proved to be one of the excellent techniques to prepare ZnO thin film with controllable properties. [ABSTRACT FROM AUTHOR]