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Various phosphonic acid based self-assembled monolayers (SAMs) have been commonly used for interface modifications in inverted perovskite solar cells. This typically results in significant enhancement of the hole extraction and consequent increase in the power conversion efficiency. However, the surface coverage and packing density of SAM molecules can vary, depending on the chosen SAM material and underlying oxide layer. In addition, different SAM molecules have diverse effects on the interfacial energy level alignment and perovskite film growth, resulting in complex relationships between surface modification, efficiency, and lifetime. Here we show that ethanolamine surface modification combined with [2-(9H-carbazol-9-yl)ethyl]phosphonic acid (2PACz) results in significant improvement in device stability compared to devices with 2PACz modification only. The significantly smaller size of ethanolamine enables it to fill any gaps in 2PACz coverage and provide improved interfacial defect passivation, while its different chemical structure enables it to provide complementary effects to 2PACz passivation. Consequently, the perovskite films are more stable under illumination (slower photoinduced segregation), and the devices exhibit significant stability enhancement. Despite similar power conversion efficiencies (PCE) between 2PACz only and combined ethanolamine-2PACz modification (PCE of champion devices ∼21.6–22.0% for rigid and ∼20.2–21.0% for flexible devices), the T80lifetime under simulated solar illumination in ambient is improved more than 15 times for both rigid and flexible devices.

AgBiS2nanocrystals are a promising nontoxic alternative to PbS, CsPbI3, and CdS quantum dots for solution-fabricated nanocrystal photovoltaics. In this work, we fabricated the first inverted (p–i–n) structure AgBiS2nanocrystal solar cells. We selected spray-coated NiO as the hole-transporting material and used PCBM/BCP as the electron-transporting material. Combining transient photocurrent and photovoltage measurements with femtosecond transient absorption spectroscopy, we investigated the charge collection process on metal oxide/AgBiS2interfaces and demonstrated that the NiO/AgBiS2NC junction in the p–i–n configuration is more efficient for charge carrier collection. The fabricated p–i–n solar cells exhibited a 4.3% power conversion efficiency (PCE), which was higher than that of conventional n–i–p solar cells fabricated using the same sample. Additionally, inverted devices showed an ultrahigh short-circuit current (JSC) over 20.7 mA cm–2and 0.38 V open-circuit voltage (VOC), suggesting their potential for further improvements in efficiency and, eventually, for large-scale production.