Photovoltaic Cell With Built-In Antenna for Internet of Things Applications

Abstract

A compact and low-profile photovoltaic (PV) cell with a built-in antenna is proposed for Internet of Things (IoT) applications. The proposed design exploits the gallium arsenide (GaAs)-based PV cell for antenna operation; for this purpose, a hexagonal slot with a trapezoidal perturbation is cut from the active area and bottom contact of the PV cell for resonance. The bottom contact of the PV cell is also used as the ground plane for the antenna. An AC blocking circuit is designed to prevent the flow of RF current toward the PV cell, and a chip inductor is used as an RF choke in the circuit. Thus, a single device simultaneously functions as a PV cell and an antenna. The GaAs PV cell shows a power conversion efficiency (PCE) of 13.25% without antireflection coating, with an open-circuit voltage (Voc), a shortcircuit current density (Jsc), and a fill factor (FF) of 0.963 V, 21.00 mA/cm 2 , and 65.52%, respectively. Furthermore, the optical transparency of the proposed PV-cell antenna is greater than 90%. The complete structure occupies an overall volume of 31.4 mm × 33 mm × 0.639 mm (0.25λo × 0.26λo × 0.0052λo at 2.45 GHz), and the antenna operates in the range of 2.14 to 2.94 GHz, with a gain of 2.8 dBi at 2.45 GHz.INDEX TERMS Compact antenna, integrated antenna, IoT devices, photovoltaic (PV) cell, slot antenna.

A broadband and high‐gain differentially fed suspended plate antenna integrated with solar cells

“…Simple stacking of solar cells and antennas limits the design integration, 1–5 whereas shading, that is, having less than 100% exposure to sunlight, decreases the solar cell utilization 3–5 . The use of the solar cell as the ground plane and its integration with the antenna improve the versatility of solar cells 6–11 . However, the upper layer components block the solar cells 6,10 (less than 100% solar cell exposure rate), and inconsistency between the radiation direction and the light‐receiving direction 7 restricts the application of solar cell antennas.…”

“…To improve compatibility, additional filter circuits have been introduced, 13–17 which is contrary to the original intention of cost reduction and miniaturization. Based on the above discussion, the solar cell SPA with high gain and wideband has obvious advantages over previously proposed designs 1–22 …”

“…Rapid development in optoelectronic devices has accelerated the integration of solar cells into wireless communication devices. In recent years, the codesign of antennas and solar cells has led to the development of smaller and lighter wireless communication devices with low power consumption and has gained considerable attention 1–22 …”

Ultra-low profile solar-cell-integrated antenna with a high form factor

“… Refs Size (λ o 3 ) IBW (%) Gain (dBi) Optical block (%) Rad. type Form factor (%) 14 1.10 × 1.10 × 0.076 4 4.1 0 Omni 25 19 1.10 × 1.32 × 0.22 52.1 9.87 0 Uni 12.5 20 1.6 × 1.2 × 0.024 15.5 8.55 0 Uni 51 23 1.27 × 1.27 × 0.056 3.35 3.5 5.3 Uni 97.3 25 4.6 × 4.6 × 0.06 6.8 20.14 12 Uni 100 26 0.62 × 1.03 × 0.06 4 3* 30 Uni 100 29 0.26 × 0.27 × 0.0054 31.49 2.8 0 Omni 90 Proposed 0.408 × 0.204 × 0.0046 5.71 2.79 …”

“…Moreover, the solar cell and antenna work independently as two separate devices. A solar cell with a built-in antenna with a resonant slot structure has been proposed to solve this problem 29 . However, the antenna has a reduced form factor due to the resonant slot in the solar cell.…”