Doc2Vec or Word2vec for word embedding
As the name implies, doc2vec generates vectors representing documents (sentences, paragraphs) but not single words. So training doc2vec won't give you word vectors but document vectors. This means you can't replace word2vec by doc2vec at all.

Here's how the authors of the underlying paper describe what doc2vec does:


  Our algorithm represents each document by a dense vector which is trained to predict words in the document.