Multifunctional Eu3+/Tb3+/Er3+-Doped Acrylate/Ionosilicas for Solar Light and Heat Management

Abstract

In the quest for advanced energy materials for smart windows, current research increasingly focuses on multifunctional, self-sustaining systems. Such materials should not only modulate sunlight and solar heat but also harvest and store solar energy. In this work, we introduce and characterize sol–gel-derived acrylate/ionosilica (AC/IS) films doped with three lanthanide (Ln = Eu3+, Tb3+, and Er3+) ions. The IS component includes a silica framework covalently bonded to 1-butyl-3-methylimidazolium ([Bmim]+) cations, with [Ln(tta)4]− anions (tta– is 2-thenoyltrifluoroacetonate) serving as counterions. The AC/IS, AC/IS-Er, and AC/IS-EuTbEr films are thin, homogeneous, transparent, hydrophilic, and thermally stable up to ca. 250 °C. At about 30 °C, the ionic conductivity values achieved were 8.3 × 10–7, 3.8 × 10–7, and 8.2 × 10–8 S cm–1, respectively. The AC/IS-EuTbEr film exhibits multimodal luminescence dominated by Eu3+ red emission and Er3+ NIR emission under UV excitation, whereas Tb3+ provides a green contribution under high-energy excitation. AC/IS-Er and AC/IS-EuTbEr convert light into heat efficiently, with the effect being more pronounced in the former sample. We demonstrate that AC/IS-EuTbEr shows excellent potential as a UV-blocking multifunctional luminescent electrolyte for electrochromic windows.