Bigger weight on recency

I have a use case where I store a date for the documents as a Unix timestamp, and I would like to weigh the most recent documents more than the older ones. Ordering by the date is not an option, as it should still order by score but just use the recency as one criteria. Can anyone come up with a solution as to how to implement this?

Just to make I sure I got you right you want the result to be ordered by score and secondary sort by date?

The results should be ordered by score anyway, but I want the score to increase on more recent dates.

So a document with very relevant content but very old date would not be as relevant as a very recent post with not as relevant content.