Method for preparing trapezoidal broadband absorption carbene squaraine dye with one-step method

The invention relates to a method for preparing a trapezoidal broadband absorption carbene squaraine dye with a one-step method. The method comprises the following steps of: fully mixing functional carbine, a squaric acid, a ligand and a solvent at the room temperature; undergoing a reflowing reaction at the temperature of 60-130 DEG C for 10-120 hours; and after the reaction, purifying to obtain the carbene squaraine dye, wherein the mass ratio of the functional carbine to the squaric acid is (20-10):(4-1). The preparation method provided by the invention is easy and practicable, has a good economic benefit, and is suitable for industrial production; and the carbene squaraine dye prepared with the method can be widely applied in the fields of nonlinear optics, photodynamics therapy, optical database storage, laser printing, biological probes, near infrared mapping, solar cells, and the like.