Researchers at the Indian Institute of Technology Bombay have developed a transparent four-terminal perovskite solar cell with a hole transport layer that enhances efficiency and stability. Incorporating Ion-Spiro HTL in perovskite solar cells improves efficiency, open-circuit voltage, and fill factor by reducing interfacial defects. The cell achieved an overall efficiency of 28.4–30.2% when integrated into tandems with commercial silicon cells, showcasing improved performance. This approach eliminates the need for bandgap-specific engineering and offers a scalable route towards highly efficient perovskite-silicon photovoltaics with enhanced stability and potential for next-generation photovoltaic technologies.