We know suleiman took help of jinns from Quran.
My question is were they evil?
Prophet Solomon didn't take their help, they were made subservient to him by Allah. The Quran mentions that the devils were included:
Quran 21:81-82 And to Solomon [We subjected] the wind, blowing forcefully, proceeding by his command toward the land which We had blessed. And We are ever, of all things, Knowing. And of the devils were those who dived for him and did work other than that. And We were of them a guardian.
Quran 38:36-38 So We subjected to him the wind blowing by his command, gently, wherever he directed, And [also] the devils [of jinn] - every builder and diver. And others bound together in shackles.