Design and Performance of Two-Sided Self-Protecting Perovskite Solar Cells for Indoor Vertical Applications

We present a novel photovoltaic architecture that integrates two perovskite solar cells (PSCs), each fabricated on a separate substrate and bonded back-to-back, forming a self-protective and bifacial device. This configuration, named two-sided self-protecting perovskite solar cell (2S-SP PSC), replaces the traditional passive glass encapsulation with a second active PSC. In a 2S-SP PSC, the active area for light harvesting doubles within a single-device footprint without increasing the overall device thickness. The two PSCs are electrically connected in series or parallel configuration and are self-encapsulated back-to-back using conventional materials that ensure mechanical integrity and further moisture protection. We realized demonstrators of the 2S-SP PSC using fully printable, HTL-free, mesoporous carbon-based AVA-MAPbI₃ PSCs, an architecture well suited for the industrial production of photovoltaic panels. Compared to single monofacial counterparts, the 2S-SP PSCs deliver nearly double the output in vertical configurations (24.6 μW vs 51.3 μW) under indoor artificial lighting (920 Lx, 6500 K). In addition, they exhibit long-term stability due to the mutual encapsulation of the two cells. An engineered 2S-SP mini-module powering a humidity/temperature sensor under ambient indoor light further highlights the potential application in self-powered IoT devices and building-applied photovoltaics.