ResearchGate generate free DOI for unpublished work

What type of research can I generate a DOI for?

DOIs can be generated for most of your unpublished work. However, publications of type Article, Book, Chapter, Patent, Cover Page, Poster , Code and Conference Paper are considered to have been published elsewhere, and therefore DOIs cannot be generated for these publication types. You can also add an existing DOI issued by your publisher to any of your research.
Note: Once a ResearchGate DOI has been generated, the research cannot be edited. Instead, you should remove the research completely, re-upload it with the edits and then generate a new DOI.

How do I generate a DOI for my research?

If a publication you’ve already added to your profile doesn’t have a DOI and isn't one of those types mentioned above, you can generate one by following these steps:

1. Go to your profile and click the Timeline tab
2. Select the publication you would like to generate a DOI for by clicking on its title
3. On the right-hand side, click on the blue arrow and select Generate a DOI (if this is not visible, then your publication is one one the types listed above; generating a DOI for these types is not possible)
4. Review the details of your publication to ensure they are correct
5. Click Generate a DOI.

To generate a DOI for unpublished work you haven't yet added to your profile you will first need to add the publication. Here's how:

1. Go to your profile and click Add your publications
2. Select the type of publication
3. Click Select file
4. Upload your file (required)
5. Click Continue
6. Verify your publication details and select Generate a DOI  (if this is not visible, then your publication is one one the types listed above; generating a DOI for these types is not possible)
7. Click Finish to confirm your changes.

Your work will now be assigned a DOI, making it easy for researchers to find and cite it.

https://explore.researchgate.net/display/support/Generating+a+DOI