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‐MAPbI 3 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.