## 6 Conclusions  
To solve the inadequate output voltage caused by low input RF power, the single-antenna RF-EH was altered to incorporate an MIMO system with multiple antennas, significantly improving voltage and efficiency. The MIMO RF-EH achieved a 95% efficiency with a peak output voltage of 6.3 V, although voltage fluctuated with RF signal strength. Despite this, the MIMO system provides key insights for developing hybrid RF-perovskite energy harvesters for low-power IoT applications. Integrating RF-EH and perovskite photovoltaic technologies holds promise for achieving sustainable and self-sufficient IoT systems, leveraging their complementary strengths and overcoming individual limitations. The study's mathematical modelling tools provide a novel approach to examining system architecture and identifying the compatibility of perovskite solar and RF-EH systems. This study demonstrates that increasing MIMO configurations can generate sufficient power, particularly at high input RF power levels (\(>\)10 dBm). However, due to the intermittent nature of high RF power, the study proposes a significant solution: integrating PSCs as an alternative energy source. This approach enhances the reliability and autonomy of IoT devices, ensuring continuous operation even during low RF input power periods. By combining MIMO RF-EH and PSC technologies, this research offers a solution that is not \begin{table}
\begin{tabular}{p{56.9 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Category** & \
\begin{tabular}{c} **Hybrid RF-PSC System** \\ **tem** \\ \end{tabular} &
\begin{tabular}{c} **Conventional Systems (Solar Panels/Battery-Powered IoT)** \\ \end{tabular} & **Remarks/Notes** \\ \hline Material Costs & Moderate, USD 50 to USD 80 per unit (PSC + RF antenna) & High, USD 100 to USD 20 per battery [72, 73, 74, 75] & PSCs are cheaper than silicon PV cells; batteries require frequent replacement. MIMO RF antennas add moderate cost. \\ \hline Installation Costs & Moderate, USD 30 to USD 50 per device & Moderate-High, USD 50 to USD 80 per device [72, 77] & Hybrid systems require integration of RF and PSCs with IoT devices; solar panels need structural support and batteries require distributed installations. \\ \hline Maintenance Costs (annually) & Low–Moderate, USD 50 to USD 10 per device & High, USD 20 to USD 30 per device [72, 77] & PSCs require encapsulation to extend illegal-pan, batteries need frequent replacement; solar panels require cleaning and periodic inspection. \\ \hline Battery Dependency & Minimal, USD 5 to USD 10 annually [46] & High, USD 10 to USD 15 per battery [79] & Hybrid systems reduce battery dependency significantly, lowering long-term costs and environmental impact. \\ \hline Lifespan & 20–25 years (with encapsulation) [72, 75, 80, 81] & 5–7 years for batteries [10–15 years for panels [79, 81] & PSC lifespan depends on encapsulation; batteries degrade faster. \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Cost–benefit comparison of hybrid RF-PSC and conventional systems. only cost-effective and high-performing but also flexible, allowing for low-temperature processing and prolonged operation without frequent battery replacements. This research offers innovative solutions for smart cities, providing sustainable power for sensors and IoT devices to enhance urban infrastructure and operations. The hybrid RF-perovskite energy harvester can be integrated into buildings, creating smarter, energy-efficient spaces while enabling wirelessly charged health-monitoring sensors in homes and public areas. The technology can also contribute to a smart economy by optimising energy use, monitoring consumption, and reducing reliance on non-renewable sources. In remote agricultural areas and critical infrastructure, it powers IoT devices for monitoring soil, crop health, and structural integrity, improving sustainability and resilience. By combining MIMO RF-EH and PSCs technologies, this research delivers a versatile, cost-effective solution for diverse applications in smart cities and remote settings.