J. form an insoluble and polymeric film of [BTA-Cu], suppressing the electrochemical corrosion and reaction between perovskite and the Cu electrode. PSCs with BTA/Cu show excellent air stability, retaining 92.8 1.9% of initial efficiency after aging for 2500 hours. In addition, 90% of initial efficiency is retained after 85C aging for over 1000 hours. PSCs with BTA/Cu also exhibit good operational stability, and 88.6 2.6% of initial efficiency is retained after continuous maximum power point tracking for 1000 hours. INTRODUCTION Perovskite solar cells (PSCs) have reached over 25% efficiency because of their extraordinary optoelectronic E260 properties (curves) is retained after maximum power point (MPP) tracking for 1000 hours. Open in a separate window Fig. 1 Working mechanism of BTA anticorrosion.(A) Device configuration and schematic diagram of BTA anticorrosion. Note that a cross-linked perovskite layer is used here according to our previous work (curves shown in fig. S11) of E260 initial efficiency after MPP tracking for 1000 hours under continuous illumination (non-normalized original data shown in fig. S13). Electrode corrosionCinduced degradation We design perovskite-based resistive random-access memory (RRAM) devices to study the ion migrationCinduced electrode reaction. Typical RRAM devices will exhibit two different states of high-resistance state (HRS) and low-resistance state (LRS) under external bias, which can be used to store information. At low bias, RRAM stays at HRS due to the resistance of perovskite itself. When increasing the bias to a certain value, the migrated I? ions in the perovskite layer start to react with the electrode and accumulate around, thus leaving many I? vacancies in the perovskite layer and forming a conductive filament for electric conduction (Fig. 6A) (curves in RRAM devices with different metal electrodes. The arrows indicate the scanning direction during measurement. DISCUSSION In conclusion, we demonstrate a chemical anticorrosion strategy to fabricate stable inverted PSCs through introducing a typical organic inhibitor of BTA. BTA chemically coordinates with a Cu electrode and form an insoluble and polymeric film of [BTA-Cu], thus E260 enhancing the corrosion-resisting ability of the Cu electrode whether under air, thermal, or operating conditions. The resulting PSCs exhibit good operational stability, retaining 88.6 2.6% of the initial efficiency after MPP tracking for 1000 hours under continuous illumination. In addition, the air and thermal stability are also greatly improved. The PSCs with BTA/Cu retain 92.8 1.9% of initial efficiency after 2500 hours of aging in moisture air and 90.7 2.5% of initial DLL1 efficiency after 1100 hours of aging at 85C. Our work highlights the role of electrode corrosion in device stability and proposes an effective method to fabricate stable inverted PSCs. Once the issue of electrode corrosion is overcome, the stability of inverted PSCs will be further improved when combining with the optimization of perovskite layer in future studies. MATERIALS AND METHODS Materials PbBr2, PbI2, MACl, MABr, FAI, C60, and TPBi are obtained from Xian p-OLED (China). BTA and TMTA (trimethylolpropane triacrylate) additive are obtained from Aladdin (China). characteristics are recorded using the Keithley 2400 SourceMeter under the solar simulator (Enlitech, SS-F5-3A) with simulated AM (Air Mass) 1.5G illumination (100 mW cm?2). The light source is a 450-W xenon lamp calibrated by a standard Si reference solar cell (Enli/SRC2020, SRC-00201). Unless otherwise stated, The curves are all measured in a glove box at room temperature E260 under a forward scan (unless otherwise stated) from 1.2 to ?0.2 V with a dwell time of 50 ms (the delay between measurement points is 50 ms). The EQE (external quantum efficiency) measurement is conducted in air using a Newport quantum efficiency measurement system (ORIEL IQE 200TM) combined with a lock-in amplifier and a 150-W xenon lamp. The light intensity at each wavelength is calibrated by one standard Si/Ge solar cell. Cyclic voltammetry and Tafel polarization curves are recorded by an electrochemical workstation (CHI660D) with a three-electrode system. SEM-EDX is recorded by SEM (FEI Quanta FEG 250) with an accelerating voltage of 20 kV. ToF-SIMS is conducted on TOF-SIMS 5 (iontof) with a sputter energy of 1 1 keV. The sample preparation is similar to PSC fabrication except that the Cu electrode is deposited without any mask. After evaporating the Cu electrode, the E260 sample is heated on hot plate at 85C in a glove box for 500 hours and then transferred.