Highly efficient low temperature solution processable planar type CH3NH3PbI3 perovskite flexible solar cells

The current density-voltage (J-V) hysteresis and power conversion efficiency (eta) of planar type CH3NH3PbI3 perovskite solar cells with TiO2 and ZnO electron conductors, which are formed by high temperature spray pyrolysis deposition at 450 degrees C and by room temperature spin-coating and subsequent heat-treatment at 150 degrees C, respectively, were compared. The ZnO based perovskite solar cells exhibited better efficiency deviation (15.96 +/- 1.07%) and less J-V hysteresis than the TiO2 based cells (15.20 +/- 1.23%) because the ZnO based cell has 1.2 fold longer charge carrier life time (tau(n)) than the ZnO based cell and the ZnO electron conductor has better electron conductivity (0.0031 mS cm(-1)) than the TiO2 electron conductor (0.00006 mS cm(-1)), thereby balancing the electron flux and the hole flux more. Due to the low temperature solution processability of the ZnO electron conductor, we could demonstrate a highly efficient PEN (poly-ethylenenaphthalate)/ITO/ZnO/CH3NH3PbI3 perovskite/PTAA/Au flexible planar solar cell with 1.1 V open-circuit voltage (V-oc), 18.7 short-circuit current density (mA cm(-2)) J(sc), 75% fill factor (FF), and 15.4% eta for the forward scan direction and 1.1 V V-oc, 18.7 mA cm(-2) J(sc), 76% FF and 15.6% eta for the reverse scan direction under illumination of 1 Sun.