Isaiah 14 contains the only reference to lucifer and it is clearly referring to the King of Babylon - just read the chapter. The Bible knows nothing of evil fallen angels.
The serpent was just that, a serpent, created with enhanced intelligence especially to present the thinking of the "flesh" so that Adam and Eve would have the opportunity of choice. See 2 Corinthians 11:3.
Here is a link to information on the website which will help with your question:
Do You Believe in a Devil? www.thisisyourbible.com/library/show/162
Here is a link to as site wich will explain some of the passages used to "prove" the existence of a fallen angel devil:
Wrested Scriptures: www.wrestedscriptures.com/b07satan/satan.html
I hope you have found this helpful.