Design and Fabrication of a Multifunctional Flexible Absorber (Flexorb) in the UV–Vis–NIR Wavelength Range

Abstract

breaking strain. [18] 4) The creasing in thin foils during fabrication and operations pose another challenge. [19] 5) The rigid and metallic foil-based absorbers will be difficult to mount on surfaces with complex geometry and curved contours. 6) The integrity of these absorbers with variety of underlying surfaces made of metals and polymers have not been established yet. To overcome some of these issues, flexible optical absorbers are developed using nanocomposites or thin metal foils as base substrate. [9,20] More recently, Zeranska-Chudek et al. has reported the flexible absorber based on grapheme/ polydimethylsiloxane (PDMS) nanocomposite with an average absorption of 95% in 400-1600 nm wavelength range. [21] The lower absorption capacity and narrow operating range is again a critical issue with this absorber. [22,23] Unavailability of an absorber which can meet all these functional requirements naturally leads to a fundamental question that how we can fabricate a near perfect flexible absorber which can overcome these issues. Here we report the fabrication of a novel flexible absorber (flexorb) with an absorbing capacity of >99% in the whole UV-vis-NIR broadband region using a simple and economical process. Apart from absorbing capacity, the mechanical integrity of flexible absorber with different types of underlying surfaces is an important parameter in order to qualify them for a variety of applications. A unified study which deals with the absorbing capacity and mechanical integrity of flexible absorbers has not been carried out to the best of author's knowledge and has been thoroughly performed in the current work. The use of PDMS as base matrix material ensures the flexibility as well as integrity of multifunctional absorber with different types of surfaces. Texturing and addition of ZnO, Fe, and carbon nanotubes (CNTs) as reinforcing fillers increases the photonic path length through multiple scattering of incident light and hence augments the absorbing capacity of PDMS. Additionally, the presence of CNTs helps to achieve impedance matching and thus significantly reduces the reflection of incident beam at absorber-surrounding interface. All these factors combined in a synergistic way and results in a near perfect absorption of incident light in the broader wavelength range of 300-2000 nm. Moreover, the flexorb shows multifunctional behavior in the sense that it can avoid environmental assisted degradation due to its observed hydrophobic and self-cleaning characteristics. In addition the improved Synthesis of a near perfect absorber is required for many technologically challenging areas. Most of the existing super absorbers are rigid and usually exploit the light in the visible range only leaving a significant part of available energy in the solar spectrum unutilized. Here the synthesis of a multifunctional flexible absorber (flexorb) with an ultrahigh absorbing capacity of >99% in the whole UV-vis-NIR region is reported. Flexorb is fabricated by texturing the polydimethylsiloxane matrix reinforced by Z...

Preparation of Ultrablack Composite Sheets with Excellent Mechanical and Chemical Stability from Sandpaper‐Based Template‐Imprinting

“…The tensile strength could be further increased to 2.3 MPa with the introduction of microcavities on the surface, which could be ascribed mainly to the trap of PANI in the pillars. [ 43 ] To further explore the mechanical stability of the composite sheet, 500 cycles of loading–unloading fatigue test were performed under the stretch strain of 0–50%. The sample could be recovered in terms of the length and width dimensions after 500 cycles as shown in Figure a.…”

Flexible Graphite Nanoflake/Polydimethylsiloxane Nanocomposites with Promising Solar–Thermal Conversion Performance

“…26,27,35 PDMS nanocomposites reinforced by combining ZnO, Fe, and CNT nanoparticles have demonstrated a similar absorption value to the ones obtained from the GnF/PDMS studied in this work. 24 The absorption in the current study can be further verified by analyzing the reflectance spectra of the nanocomposite films. While pure PDMS transmitted around 92% of light, incorporation of GnF, even at 1 wt %, significantly diminishes the transmittance down to less than 0.2% in the entire spectrum, indicating that all GnF/PDMS nanocomposites studied in this work are opaque (Figure S6).…”

“…20−24 Due to superior absorption capabilities and their photostability, carbon-based photothermal materials such as graphite, CNT, graphene flakes, and carbon nanoparticles have been used to fabricate PDMS nanocomposites for various solar-powered applications. [20][21][22]24,25 In particular, graphite is often the immediate choice because of its lost cost and ease of availability. 25−29 However, natural graphite has higher reflectance at the air−dielectric interface, limiting solar energy absorption.…”

“…In this regard, flexible polydimethylsiloxane (PDMS)-based nanocomposites integrating photothermal conversion media have evoked unprecedented interest as they can be fabricated as 3D porous structures and thin films or can be applied as coatings on various structural supports and complex geometries. − Due to superior absorption capabilities and their photostability, carbon-based photothermal materials such as graphite, CNT, graphene flakes, and carbon nanoparticles have been used to fabricate PDMS nanocomposites for various solar-powered applications. − ,, In particular, graphite is often the immediate choice because of its lost cost and ease of availability. − However, natural graphite has higher reflectance at the air–dielectric interface, limiting solar energy absorption. In addition, the absence of chemical functional groups on the graphite surface makes it less compatible with polymer structures.…”

Near perfect thin film flexible broadband optical absorber with high thermal/electrical conductivity

“…For safeguarding optical instruments present on the satellites and to suppress stray light, various types of black coatings are developed in past few years . Most of these black surfaces are fabricated using surface texturing, optical grating, etching, nano composite or by applying coating of different nanomaterials on the surface of interest. It is observed that the surface texturing/etching followed by nano‐coating shows enhanced light trapping capacity in a broader wavelength range.…”