Zigzag-edged triangular graphene nanofragments(TGNFs),known as open-shell polycyclic aromatic hydrogencarbons(PAHs),have drawn enormous research attention in the field of synthetic organic spin chemistry and materials science due to their amazing electronic and magnetic properties.Based on extensive spin-polarized density functional theory calculations,we show that TGNFs can be used as building blocks to design ferromagnetic oligomers and two-dimensional(2D)lattices.These diverse TGNF-based oligomers and 2D lattices are stable and their ground states are ferromagnetic.The strong magnetic coupling in these proposed ferromagnetic oligomers and 2D lattices leads to the high Curie temperature(up to 700K).Moreover,we find that these 2D lattices are good bipolar magnetic semiconductors.Considering these predicted stability,diversity and ferromagnetism,TGNFs hold great potential for building room-temperature ferromagnetic materials for various applications.