  It is known that iron selenide superconductors exhibit unique characteristics
distinct from iron pnicitides, especially in the electron-doped region.
However, acomprehensive study of continuous carrier doping ang the
corresponding crystal structures of FeSe is still lacking, mainly due to the
difficulties in controlling the carrier density in bulk materials. Here, we
report the successful synthesis of a new family of bulk Lix(C3H10N2)0.37FeSe,
which features a continue superconducting dome harboring Lifshitz transition
within the wide range of 0.06~0.68. We demonstrate that with electron-doped,
the anion height of FeSe layers deviates lineraly away from the optimized
values of pnictides and pressurized FeSe. This feature leads to anew
superconducting zone with unique doping dependence of the electronic structures
and strong orbital-selective electronic correlation. Optimal superconductivity
is achieved when the Fe 3d t2g orbitals have almost the same intermediate
electronic correlation strength, with moderate mass enhancement between 3~4 in
the two separate superconducting zone. Our result shed light on archieving
unified mechanism of superconductivity in iron-based materials.
