Study of interface engineering on perovskite-based indoor photovoltaics for powering Internet-of-Things

Research on perovskite-based indoor photovoltaics (PeIPVs) has attracted significant interest in Internet of Things (IoT) sensors owing to their potential use as power sources. This interest stems from the fact that PeIPVs offer advantages such as a suitable bandgap for indoor light sources, light-emitting diode (LED), and excellent defect tolerance. However, because the intensity of indoor LED light sources is 333 times weaker than that of 1 sun (AM1.5G, 100 mW cm⁻²), charge recombination in PeIPVs changes compared with that in conventional solar cells, shifting from bimolecular recombination to trap-assisted recombination. Given these differences, the research methodology for PeIPVs requires a focus on controlling the interfacial defects, diverging from conventional solar cell research approaches. In general, the interfaces between the perovskite and other layers in perovskite-based photovoltaic devices have a relatively high trap density compared to the interior of the perovskite, owing to incomplete reactions or non-ideal heterojunctions. The interfacial defect-sensitive property of IPV has prompted researchers to address these challenges through various interface engineering techniques such as surface treatment, electron transport layer (ETL)/hole transport layer (HTL) engineering, and precursor engineering, significantly improving efficiency. In this review, we discuss the research outlook by analyzing the trends and critical factors in PeIPVs and research based on interface engineering around perovskite interfaces. Furthermore, the potential applications of PeIPV research are outlined through examples such as flexible configurations and modularization for powering real-world Internet of Things sensors.