Ultra-flatbands in twisted penta-hexa-CB bilayer with large twist angles

We report the discovery of ultra-flatbands in twisted penta-hexa-carbon boron (PH-CB) bilayers, a finding with profound implications for condensed matter physics. Using first-principles calculations, we show that PH-CB bilayers exhibit an exceptionally narrow bandwidth of 0.13 meV at a distortion angle of 9.6°, indicating the robust electron correlation effects. This observation contrasts with the need for tiny twist angles in graphene to achieve similar effects. The PH-CB system, with its indirect bandgap of 2.11 eV, represents a versatile platform for exploring novel electronic phenomena that may lead to advances in quantum materials. Our results highlight the inverse relationship between wave function localization and bandwidth and provide a new perspective for the design of two-dimensional materials with tailored electronic properties.