Why homoannuler diene have higher lamda max?

Homoannular dienes have a higher λ max in their UV-Vis absorption spectra due to the extended conjugation and the presence of additional π-electrons compared to non-homoannular systems. The increased electron delocalization lowers the energy gap between the ground and excited states, allowing for absorption of longer wavelengths (lower energy light). Furthermore, the structural features of homoannular dienes can facilitate more effective π-π* transitions, contributing to their higher λ max.