Coupling vanadium oxide and lead-free perovskite for sustainable passive daytime radiative cooling

A key factor in effectively integrating passive daytime radiative coolers (PDRC) into the built environment is conferring them the ability to adapt to external stimuli. Vanadium Dioxide (VO 2 ) has been proposed for radiative cooling applications due to its reversible insulator-to-metal transition, which induces significant changes in optical properties. However, the aesthetic limitations of black VO 2 and highly reflective metallic substrates have hindered widespread adoption in urban contexts. This study introduces a novel approach by coupling the temperature-dependent switchable behavior of VO 2 with the tunable bandgap properties of lead-free perovskite nanocrystals to develop scalable, self-regulating radiative coolers. VO 2 was synthesized via two strategies —polyol and hydrothermal (T t r a n s i t i o n =66 °C–64 °C)— and incorporated into a polymer matrix to produce PMMA films with varying VO 2 concentrations. Comprehensive thermo-optical and morphological analyses were conducted to identify the most suitable configurations for integration into PDRC devices ( τ s o l = 0 . 90 , ϵ M I R = 0 . 76 ). Additionally, incorporating lead-free perovskites into PMMA resulted in scalable colored layers with excellent photoluminescent emissions ( λ e m i s s i o n =420,525,580 nm). The combination of VO 2 -perovskite multilayers with reflective substrates offers an innovative strategy for PDRC applications. The resulting structures exhibit dynamically adaptive thermal emission and a twofold shortwave radiation rejection mechanism — reflection and photoluminescence — positioning them as promising solutions for urban environments. • Vanadium oxide (VO 2 ) enables dynamic adaptivity in radiative cooling devices. • Hydrothermal and polyol VO 2 syntheses were performed and comparatively analyzed. • Scalable thermochromic films were created by embedding VO 2 into a polymer matrix. • Lead-free perovskites ensure color tuning and integration into urban environments. • An adaptive-colored PDRC combines thermochromic VO 2 and photoluminescent perovskites.