SnO₂ Quantum Dot-Modified Mesoporous TiO₂ Electron\nTransport Layer for Efficient and Stable Perovskite\nSolar Cells

Abstract

As\na revolutionary photovoltaic technology, the perovskite solar\ncell has received enormous attention, owing to excellent electronic\nand optical properties of perovskite materials. The mesoporous TiO₂ (m-TiO₂) framework is extensively used as an electron\ntransport layer (ETL) to construct high-performance perovskite solar\ncells (PSCs), showing efficient electron extraction capability, owing\nto the enlarged perovskite/ETL interface. However, the TiO₂ ETL usually involves high-density oxygen vacancies, low electron\nmobility, and relatively high photocatalytic activity toward perovskite\nmaterials. To address such issues, herein, we demonstrate the successful\nconstruction of SnO₂ quantum dot (QD)-modified m-TiO₂ as an effective ETL for PSCs. It is revealed that the SnO₂ QD-modified m-TiO₂ ETL affords more favorable\nelectron extraction and transport characteristics and suppressed charge\nrecombination, resulting from the interfacial passivation and the\nenhanced conductivity of ETLs. Furthermore, the ultrathin SnO₂ QD layer incorporated at the m-TiO₂/perovskite\ninterface effectively lowers the photocatalytic activity of TiO₂ toward perovskite materials, thereby improving the long-term\ndevice stability. Eventually, the MAPbI₃- and FAPbI₃-based PSCs utilizing the SnO₂ QD-modified m-TiO₂ ETLs obtained appreciable power conversion efficiencies of\n19.09 and 20.09%, respectively, higher than those of counterpart devices\nbased on the conventional m-TiO₂ and SnO₂ ETLs.