Graphene-based autonomous pyroelectric system for near-field energy conversion

Abstract

In the close vicinity of a hot solid, at distances smaller than the thermal wavelength, a strong electromagnetic energy density exists because of the presence of evanescent field. Here we introduce a many-body conversion principle to harvest this energy using graphene-based pyroelectric conversion devices made with an active layer encapsulated between two graphene field-effect transistors which are deposited on the source and on the cold sink. By tuning the bias voltage applied to the gates of these transistors, the thermal state and the spontaneous polarization of the active layer can be controlled at kHz frequencies. We demonstrate that the power density generated by these conversion systems can reach $$130\,{\rm mW\,cm}^{-2}$$ 130 mW cm - 2 using pyroelectric Ericsson cycles, a value which surpasses the current production capacity of near-field thermophotovoltaic conversion devices by more than three orders of magnitude with low grade heat sources ($$T<500\,{\rm K}$$ T < 500 K ) and small temperature differences ($$\Delta T\sim 100\,K$$ Δ T ∼ 100 K ).

Near-field radiative heat transfer in hyperbolic materials

“…There have been some explorations of NTPVs using conventional materials that reduce the vacuum distance to the nanometer level for increased efficiencies [12][13][14][15][16][17][18][19][20][21][22][23]. Hyperbolic materials are ideal high-temperature heat sources because of their large wavevector transmission characteristics.…”

“…As a result, the near-field radiative heat transfer (NFRHT) can exceed the blackbody limit by orders of magnitude [6][7][8][9]. The significant radiative heat flux in the near field provides a new route for many potential applications [10,11], such as TPV [12][13][14][15][16][17][18][19][20][21][22][23], thermal rectification [24][25][26][27][28][29][30][31][32][33][34][35][36], noncontact refrigeration [37-41], and thermal transistors [42]. As large heat fluxes are critical in such applications, continuous efforts have been devoted to highly efficient near-field heat transport.…”

High Resolution Measurement of Near-Field Radiative Heat Transfer enabled by Nanomechanical Resonators

“…For example, mechanical oscillations coupled with near-field thermal radiation could be used for implementing systems that rely on temperature oscillations for converting heat to electricity, exploiting for example pyroelectric materials. 70,71 Ultra-low dissipation of SiN mechanical oscillators could also allow simultaneous characterization of Casimir forces 72 and NFHT.…”