The Shockley-Queisser(SQ) limit sets an upper limit on the efficiency of conventional semiconductor photovoltaic devices. A thermophotovoltaic system(consisting of a heat source

a spectrally selective emitter and low bandgap photovoltaic cell) can work as an alternative to break this theoretical efficiency limit. To further improve the power generation efficiency of thermophotovoltaic(TPV) systems

an emitter with a multilayer cross structure based on metamaterials was designed in this work. Through optimization of its geometric size

the emitter demonstrates an excellent narrow-band emission spectrum. This effectively reduces the loss of low-energy photons below the bandgap of PV cells and avoids the absorption of high-energy photons that exacerbate lattice vibrations to cause thermal losses. Its application to TPV systems enables a perfect match with In0.69Ga0.31As cells with a bandgap of 0.6 eV. Detailed theoretical calculations of this TPV system show that the power generation efficiency can exceed the Shockley-Queisser(SQ) limit(41%) at 1 117 ℃

and will be further improved as the emitter temperature increases. When the temperature reaches 2 000 K

the efficiency is as high as 46.75%. Additionally

the narrowband emitter shows good angular insensitivity in the range of 0～60 degrees.