  In this work, we report multiple intercalation stages and universal Tc
enhancement of superconductivity in 1T-SnSe2 through Li and organic molecules
cointercalation. We observe significantly increased lattice parameters up to 40
{\AA} and dramatically enlarged interlayer distance up to ~11{\AA} in Li and
N,N-dimethylformamide (DMF) cointercalated SnSe2. Well-separated
cointercalation stages with different stacking patterns have been discovered by
carefully controlled reaction time and concentration of solutions. These
cointercalation stages are superconductors showing different superconducting
signals. In addition, Li and various organic species such as Acetone, Dimethyl
sulfoxide (DMSO) and Tetrahydrofuran (THF) have been cointercalated into SnSe2
crystals, all of which show enhanced superconducting Tc compared to solely Li
intercalated SnSe2. Our findings may provide more insight to effectively tune
electronic structure of the lamellar structure through organic molecules
co-regulation, and open a new strategy to engineer the physical properties of
these layered materials by controlling their different intercalation stages.
