Advancing inverted (p-i-n) perovskite solar cells (PSCs) is key to further enhance the power conversion efficiency (PCE) and stability of flexible and perovskite-based tandem photovoltaics. Yet, the presence of defects...

One of the key challenges of perovskite photovoltaics is the scalable fabrication of high‐efficiency perovskite solar cells (PSCs). Not only the scalable deposition of high‐quality perovskite thin‐films itself, but also the adjacent charge extraction layers is pivotal. In this work, PSCs based on all‐inkjet‐printed absorber and extraction layers are presented, allowing for a scalable and material‐efficient deposition. The inkjet‐printed PSCs are of p–i–n‐architecture with a precursor‐based nickel oxide hole‐transport layer, a high‐quality inkjet‐printed triple‐cation (methylammonium, formamidinium, and cesium) perovskite absorber layer and a double layer electron‐transport layer of phenyl‐C61‐butyric acid methyl ester and bathocuproine. The ink properties, inkjet parameters, and annealing procedure are optimized for each layer. PSCs with such inkjet‐printed absorber and charge carrier extraction layers demonstrate an efficiency of >17% with low hysteresis. Although printed in ambient atmosphere, the devices show excellent short‐term stability (40 h) even under elevated temperature (85 °C). These results are a promising next step on the way to fully inkjet‐printed perovskite solar cells, including both electrodes as well.

In this work, we introduce a bilayer ETL composed of lithium (Li)-doped compact SnO2 (c-SnO2) and potassium-capped SnO2 nanoparticle layers (NP-SnO2) to enhance the electron extraction and charge transport properties in perovskite solar cells, resulting in an improved PCE and a strongly reduced J–V hysteresis.

The electronic level alignment at interfaces plays an important role in the development and optimization of organic semiconductor devices. While organic heterointerfaces are well studied, photoelectron spectroscopy on homointerfaces is challenging. As the emissions of the substrate and the adsorbate layer are dominated by the same spectral features, it is nearly impossible to distinguish their layer origin. In this study, we accept this challenge and analyze the interface between doped and undoped layers consisting of the same hole transport molecule (HTM). We used X-ray and ultraviolet photoelectron spectroscopy to monitor the stepwise thin film deposition of the well-known 4,4′,4″-tris[phenyl-(m-tolyl)amino]triphenylamine (m-MTDATA) molecule as well as a state-of-the-art triarylamine-based molecule synthesized at Merck KGaA. The interpretation of the data is enabled by a fitting procedure based on an energetic disorder model. First, as a test case, heterointerfaces of step by step deposited, differently p-doped HTMs on indium tin oxide are analyzed, revealing the power of the model for an accurate description of the data while enabling detailed discussions of the model by comparison to classical PES data analysis. Second, homointerfaces of the intrinsic HTMs on their p-doped sublayers are studied. Here, we observe an unexpected space charge region in the p-doped sublayer. Within the boundaries of our model, we obtain good fits of spectra by introducing an increased number of electronic states right at the interface in the undoped layer.

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