The dissertation process posses a substantial logistical challenge to researchers, who must take in and analyze more articles than can be held in their memories. The most successful researchers will plan for this by putting a strong organization system in place. Some researchers utilize their bibliographic utility (RefWorks, Zotero, etc.), database folders, or Google Scholar's my library folders. Whatever method you choose needs to work well for you, and be implemented early on in your research. Once the articles start piling up, it can be difficult to go back!
I personally used multiple approaches:
First, I used my normal bibliographic utility (RefWorks) to save my citations and build my bibliography. I recommend capturing every citation that looks even remotely interesting. You can always delete the items which don't pan out for you. It's much harder to find the good articles that you didn't save after the fact.
Next, I immediately downloaded the article PDF, and saved it into my folders. I utilized a shared drive in Google Drive, which was shared among my entire committee. That also made it much easier for me to communicate with my committee, as we all had access to the same information in real time.
Finally, as I read each article, I used a Google Drive spreadsheet to capture relevant information about each, and to "tag" them with the big idea or important themes. Once I had absorbed all of my lit review articles and entered them in the spreadsheet, I then sorted the spreadsheet by theme. This enabled me to easily see clusters of ideas, which helped so much with synthesis. Additionally, having my notes and thoughts about each article captured in one central location was so helpful during the writing process, as I had long since forgotten the contents of each specific article.