Conjugated　PEDOT　is　considered　as　a　promising　electrochromic　(EC)　material,　while　the　unsatisfactory　optical　modulation　contrast　limits　its　applications.　Enhancing　the　conjugated　chain　length　has　been　proved　to　improve　the　EC　performance　of　conjugated　conductive　polymers　(CPs).　Herein,　a　simple　and　effective　solvent-induced　approach　is　developed　to　prepare　EC　PEDOT　with　extended　conjugated　chains.　A　strong　polarity　solvent　of　acetonitrile　is　employed　to　electrochemically　polymerize　PEDOT　on　a　well-designed　Ni(OH)(2)　nanosheet　arrays　substrate,　which　facilitates　a　longer　conjugated　chain　formed　in　the　PEDOT　molecules.　Compared　with　the　samples　obtained　in　water,　the　acetonitrile-assistant　prepared　PEDOT　demonstrates　a　superior　EC　behavior,　including　enhanced　transmittance　contrast　(-48%　at　550　nm),　fast　response　for　coloring/bleaching　(1.35　s/0.83　s),　ultrahigh　coloration　efficiency　(293.6　cm(2)　C-1)　and　improved　cycling　durability.　Particularly,　a　stable　optical　modulation　could　be　maintained　in　a　wide　temperature　range　(-10　to　100　degrees　C)　and　harsh　acidity　environment.　This　work　is　anticipated　to　provide　a　novel　and　simple　approach　to　lengthen　the　conjugated　chains　of　EC　PEDOT　toward　enhanced　optical　modulation　and　can　also　be　applicable　to　various　conjugated　CPs.