Electrochimica Acta, Vol.236, 341-348, 2017
Enhanced Efficiency and stability of Perovskite Solar Cells using Porous Hierarchical TiO2 Nanostructures of Scattered Distribution as Scaffold
A type of quasi-mesoscopic perovskite solar cells (QM-PSCs) with porous hierarchical TiO2 (hier-TiO2) nanostructures of scattered distribution as scaffold was investigated. The porous hier-TiO2 nanostructures were synthesized by sintering MIL-125(Ti) of metal-organic frameworks (MOFs) at 500 degrees C in air and which were partly inherited from the ordered porosity of MIL-125(Ti). The ordered hier-TiO2 nanostructures were scattered on compact TiO2 layer to form a quasi-mesoscopic scaffold of scattered distribution, which can offer enough growth space for perovskite grains and promote the ordered growth of perovskite grains. The QM-PSCs shows a power conversion efficiency (PCE) of 16.56%, much higher than PCE (11.38%) of PSCs with conventional small TiO2 nanoparticles (npt-TiO2) as scaffold and PCE (6.07%) of planar PSCs with compact TiO2 layer. The PCEs of PSCs with hier-TiO2 and npt-TiO(2)main 47% and 22% of the initial PCE values aging for 30 days in air, indicating that PSCs with hier-TiO2 scaffold shown better stability and moisture resistance. The enhanced performance of QM-PSCs is primarily attributed to the superior wettability quasi-mesoscopic scaffold with ordered porous hier-TiO2 nanostructures, which help to form the high quality perovskite film with better crystillinity and less pin-holes, and improve the contact properties between perovksite and electron transport layer. (C) 2017 Elsevier Ltd. All rights reserved.