• Simplified Architecture: Researchers developed a "fully stripped-down" solar cell by removing the Electron Transport Layer (ETL) and Hole Transport Layer (HTL), significantly reducing manufacturing complexity and cost. • Chemical Enhancement: By introducing EMIM Ac into the perovskite layer, they improved energy alignment and crystallinity to overcome the efficiency losses usually found in simpler cell designs. • Practical Application: The resulting cell achieved an efficiency of 12.53% under indoor lighting, proving it is a viable, low-cost power source for energy-frugal Internet of Things (IoT) devices. Perovskite solar cells (PSCs) offer a promising pathway towards low-cost, high-efficiency photovoltaics. However, conventional PSCs require at least two charge transport layers (ETL and HTL), increasing fabrication complexity and cost. ETL-free PSCs present a cost-effective alternative but suffer from energy-level misalignment at the perovskite/electrode interface, leading to charge recombination and efficiency losses. Recent studies have employed interfacial modifications to improve energy alignment, yet these still retain multilayer structures. In this work, we developed a simplified, fully ETL- and HTL-free PSC architecture (FTO/Cs 0.1 (FA 0.88 MA 0.12 )Pb(I 0.7 Br 0.3 )(CsFAMA 1.7 eV)/Phenethyl ammonium iodide (PEAI)/Carbon) via introducing 1-ethyl-3-methylimidazolium acetate (EMIM Ac) into the perovskite layer, causing better energy level alignment, reduced trap density, and improved crystallinity. The fully striped-down structure surprisingly achieves an efficiency of 12.53% under 1,000 lux, sufficient to be a battery replacement for indoor energy frugal IoTs, while lowering production costs by minimizing layers and processing steps. Our findings highlight ultra-lean PSCs, which comprise of only perovskite and two electrodes, demonstrating the simplified solar cell structure to date, which is fully capable of powering indoor IoT applications.
Kamjam et al. (Wed,) studied this question.