I was trying to understand scalar field models of dark energy which are motivated by inflationary cosmology. The motivation is that we may also explain the late-time acceleration using scalar fields(e.g quintessence, k-essence etc.). Anyway the following textbook was useful for me.
Cosmological Inflation and Large-Scale Structure by Andrew R. Liddle & David H. Lyth (2000, Cambridge University Press).
And, I also recommend the other lecture notes & documents prepared by Liddle. For example An introduction to cosmological inflation (arXiv:astro-ph/9901124)
His materials are highly pedagogical and have rigorous math.