Economical Perovskite Solar Cell Enabled by Triple Cost‐Reduction Strategies

Perovskite solar cells (PSCs) are emerging as a promising technology for indoor photovoltaics due to their high efficiency and cost‐effective manufacturing. In this article, three strategies are explored to reduce costs and enable perovskite materials (PSK) as power sources for indoor internet of things (IoTs): 1) using dual perovskite absorber layer (PSK1/polyethylene glycol (PEG)/PSK2) to replace both the absorber and hole transport layers, 2) utilizing spray‐coating for perovskite deposition under ambient conditions with 45%–65% relative humidity (RH), and 3) replacing metal electrodes with carbon electrodes. The dual absorber layer improves charge transport, while the spray‐coating process minimizes solution waste, making large‐scale production more feasible. Additionally, the use of PEG as an interlayer effectively enhances defect passivation, improving charge transport and stability. The proposed carbon‐based device architecture offers the lowest material cost ($11.98 m −2 ) and the modified levelized cost of electricity for indoor light (m‐LCOE‐i) of 1.54 ¢ Wh −1 , outperforming traditional Spiro‐OMeTAD/Au or carbon designs along with enhancing the commercial viability of PSCs. To demonstrate its practicality, connected PSCs are utilized to power IoT devices for over a month under typical laboratory lighting conditions (300–400 lux) at 40%–65% RH.