TiO2 nanoparticle is employed as mesoporous scaffold under low temperature in methylammonium lead iodide (MAPbI(3)) perovskite layer for planar heterojunction solar cells (PH PSCs). It has been found that the high quality perovskite crystalline is obtained by adding TiO2 nanoparticles into perovskite layer. The incident photon to current conversion efficiency (IPCE) has been significantly improved due to the enhanced light scattering of TiO2 nanoparticles and efficient electron transport in perovskite layer. Specially, interconnected TiO2 nanoparticles improves the electron transport property, leading to reducing hysteresis and obtaining the much higher power conversion efficiency (PCE) (12.96%) with V-oc = 0.99 V, J(sc) = 22.9 mA/cm(2) and FF = 0.562. This fabrication method is promising for flexible PH PSCs application and reducing the preparation cost. (C) 2017 Elsevier Ltd. All rights reserved.