Nowadays the major factors determining commercialization of lead halide perovskite photovoltaic technology are shifting from solar cell performance to stability, reproducibility, up-scaling, and in particular the concern of Pb leakage during solar cell operation. Here we simulate a realistic scenario that the perovskite solar modules with different encapsulation methods are damaged to a typical extent by mechanical impact (according to the modified FM 44787 standard) and quantitatively measure the lead leakage rates from the damaged modules. We demonstrate that an epoxy resin (ER) based encapsulation method reduces the Pb leakage rate by a factor of 375 compared to the encapsulation method using a glass cover with the UV-resin cured at the module edges. The excellent Pb leakage prevention characteristics is due to the self-healing property of ER and increased mechanical strength. These findings strongly suggest lead halide perovskite photovoltaic products can be used with minimal Pb leakage if appropriate encapsulation is employed.

Upscaling of perovskite solar cells to module scale and affording long-term stability have been recognized as the most important challenges for commercialization of this emerging photovoltaic technology. In a perovskite solar module (PSM), each interface within the device contributes to the efficiency and stability. Here, we employ a holistic interface stabilization strategy by modifying all the relevant layers and interfaces, namely the perovskite layer, charge transporting layers and the device encapsulation to improve the efficiency and stability of PSMs. The treatments were selected to be compatible with low-temperature scalable processing and the module scribing steps. Our unencapsulated PSM achieved a reverse-scan efficiency of 16.6% with a designated area of 22.4 cm 2 . The encapsulated PSM retained approximately 86% 2 of the initial performance after continuous operation for 2000 h under AM 1.5G light illumination, with translates into a T 90 lifetime of 1570 h and an estimated T 80 lifetime of 2680 h.

An amino‐functionalized copolymer with a conjugated backbone composed of fluorene, naphthalene diimide, and thiophene spacers (PFN‐2TNDI) is introduced as an alternative electron transport layer (ETL) to replace the commonly used [6,6]‐Phenyl‐C61‐butyric acid methyl ester (PCBM) in the p–i–n planar‐heterojunction organometal trihalide perovskite solar cells. A combination of characterizations including photoluminescence (PL), time‐resolved PL decay, Kelvin probe measurement, and impedance spectroscopy is used to study the interfacial effects induced by the new ETL. It is found that the amines on the polymer side chains not only can passivate the surface traps of perovskite to improve the electron extraction properties, they also can reduce the work function of the metal cathode by forming desired interfacial dipoles. With these dual functionalities, the resulted solar cells outperform those based on PCBM with power conversion efficiency (PCE) increased from 12.9% to 16.7% based on PFN‐2TNDI. In addition to the performance enhancement, it is also found that a wide range of thicknesses of the new ETL can be applied to produce high PCE devices owing to the good electron transport property of the polymer, which offers a better processing window for potential fabrication of perovskite solar cells using large‐area coating method.

The contact between the n-type interlayer and the donor provides an extra interface for charge dissociation.

Perovskite solar cells (PSCs) have attracted great attention in the past few years due to their rapid increase in efficiency and low‐cost fabrication. However, instability against thermal stress and humidity is a big issue hindering their commercialization and practical applications. Here, by combining thermally stable formamidinium–cesium‐based perovskite and a moisture‐resistant carbon electrode, successful fabrication of stable PSCs is reported, which maintain on average 77% of the initial value after being aged for 192 h under conditions of 85 °C and 85% relative humidity (the “double 85” aging condition) without encapsulation. However, the mismatch of energy levels at the interface between the perovskite and the carbon electrode limits charge collection and leads to poor device performance. To address this issue, a thin‐layer of poly(ethylene oxide) (PEO) is introduced to achieve improved interfacial energy level alignment, which is verified by ultraviolet photoemission spectroscopy measurements. Indeed as a result, power conversion efficiency increases from 12.2% to 14.9% after suitable energy level modification by intentionally introducing a thin layer of PEO at the perovskite/carbon interface.