Motivated by the success of 9,9'-spirobifluorene (SBF) in optoelectronic materials, we synthesized a novel spiro compound, spirophenanthrene (SP). Incorporating a phenanthrene unit as the core, we aimed to leverage the π-conjugation of SPs to surpass the limitations of SBF. Experimental and theoretical studies revealed significant advantages over SBF, including red-shifted wavelengths, tunable LUMO energy levels, and enhanced thermal stability. These advantages suggest the potential of SPs as versatile building blocks for diverse optoelectronic devices.