Peat moss is a soilless medium. In other words it's not comprised of any sand, silt, or clay particles.
Nitpicking aside, it's a wonderful growing medium for a number of reasons. Arguably the most important is that it has EXCELLENT water retention, so make sure you also have excellent drainage when growing in it, or you can drown your plants. It is very acidic, but this can be corrected with limestone, or better yet, a product like General Organics CaMg+, as peppers need adequate Ca and Mg both to avoid Blossom End Rot (BER). The consistency is too fine to use on its own, so perlite and vermiculite are both great additional amendments, because they improve the structure of the media, water retention, and have good Cation Exchange Capaticies (CEC's). Sand and mulch are also good. My 5-gallon plants have a potting mix that is roughly 65% peat and they love it.