Thermosensitive poly(N-vinylcaprolactam) as a transmission light regulator in smart windows

• Published in: Solar energy materials and solar cells Vol. 186; pp. 266 - 272
• Main Authors: Sala, Renata L., Gonçalves, Ricardo H., Camargo, Emerson R., Leite, Edson R.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.11.2018; Elsevier BV
• Subjects: Charge transfer; Electrochromism; Joule heating; Kinetics; N-vinylcaprolactam; Ohmic dissipation; Optical properties; Optics; Power supply; Reaction kinetics; Resistance heating; Smart materials; Solar energy; Stimuli-sensitive materials; Substrates; Switchable devices; Temperature dependence; Thermosensitive polymer; Transparent conducting substrates; Transparent conducting substrates; Switchable devices; Thermosensitive polymer; Stimuli-sensitive materials; Joule heating
• ISSN: 0927-0248; 1879-3398
• DOI: 10.1016/j.solmat.2018.06.037

Upcoming generation of smart windows requires simple design, fast stimulus response and cost-effective production. Aiming these features, we reported a new approach of switchable devices based on the thermosensitive polymer poly(N-vinylcaprolactam) (PNVCL) and facile assembly of the components (FTO layers and polymer). Its optical/color change from transparent to opaque is temperature-dependent and activated by induced Joule heating of conductive substrates. Therefore, the reported devices showed fast reversible response (less than 60 s) by small input power and adjustable opaqueness according to polymer concentration. In opposite to traditional electrochromic smart windows dependence of the kinetics charge-transfer reaction, the observed features are triggered by the thermodynamic mechanism of the reversible coil-globule transition from PNVCL suspension, which can lead to stable performance of the proposed device. [Display omitted] •Joule heating induces the color modulation of poly(N-vinylcaprolactam) suspension.•Thermodynamic aspects regulate the fine-tuning of smart window transparency.•Smart windows have high modulation luminous transmittance under an applied bias.•Dependence of smart window transmittance with polymer concentration.