Spiro[fluorene-9

9'-xanthene] (SFX) is one of the versatile molecular building blocks of organic/polymer semiconductors

which is widely applied in the construction of luminescent

charge transport and trapping materials in organic optoelectronics. In the early stage

SFX without any substituent could only be synthesized by multi-step o-halobiaryl method. In 2006

Wei Huang and Ling-hai Xie (Huang-Xie) fortuitously discovered the one-pot synthesis of SFXs

which effectively solved the problem of multisteped synthesisof building blocks in organic non-plane semiconductor

and further expanded the scope of substrates of azafluorene and aromatic amine compounds

finally coined as the "Huang-Xie method" of SFXs. This method has the advantages of simple steps

high yield and low cost

which is highly highlighted by chemists in MIT and named by Japanese scientists

and extensively adopted by the peers for the design of steric semiconductors. The industry has successfully achieved the mass production of SFXs by virtue of the high efficiency of the Huang-Xie method. Up to date

SFX has been widely exploited in academia and industry by replacing 9

9'-spirobifluorene (SBF)

especially in the organic light-emitting diode (OLED) display technology from LG Company in South Korea.