In Situ Energetics Modulation Enables Efficient and Stable Inverted Perovskite Solar Cells

In contrast to conventional (<i>n-i-p</i>) perovskite solar cells (PSCs), inverted (<i>p-i-n</i>) PSCs offer enhanced stability and integrability with tandem solar cell architectures, which have garnered increasing interest. However, <i>p-i-n</i> PSCs suffer from energy level misalignment with transport layers, imbalanced transport of photo-generated electrons and holes, and significant defects with the perovskite films. Here, we introduce tris(2,4,6-trimethyl-3-(pyridin-3-yl)phenyl)borane (3TPYMB), a nonionic <i>n</i>-type molecule that, through hydrogen bonding and Lewis acid-base reactions with perovskite surfaces or grain boundaries, enables in situ modulation of perovskite energetics, effectively mitigating the key challenges of <i>p-i-n</i> PSCs. The in-situ energetic strategy with 3TPYMB enables simultaneous improvements on these three fronts that limit the performance of <i>p-i-n</i> PSCs: aligning the energy levels of the perovskite with those of the transport layers, balancing electron and hole transport within the perovskite, and reducing defects in both the bulk and surface of the perovskite.<br/>As a result, the champion <i>p-i-n</i> PSCs achieved a certified quasi-steady-state power conversion efficiency of 24.55 ± 0.33 %, with a reverse scan efficiency of 25.58%, as certified by the accredited third-party NREL PV laboratory. These PSCs also exhibited exceptional stability, with unencapsulated devices retaining 97.8% of their initial efficiency after 1,800 hours of continuous operation at maximum power point under N₂ atmosphere, 1-sun illumination, and 60 °C conditions. Supported by both theoretical and experimental evidence, this work provides a multifaceted solution for overcoming the barriers that have hindered the progress of efficiency and stability of <i>p-i-n</i> PSCs, pushing PSC performance to new heights.