Abstract We introduce a general method for constructing modules for 0-Hecke algebras and supermodules for 0-Hecke–Clifford algebras from diagrams of boxes in the plane, and give formulas for the images of these modules in the algebras of quasisymmetric functions and peak functions under the relevant characteristic map. As initial applications, we resolve a question of Jing and Li (J Combin Theory Ser A 135:268–290, 2015), introduce a new basis of the peak algebra analogous to the quasisymmetric Schur functions, uncover a new connection between Schur Q-functions and quasisymmetric Schur functions, give a representation-theoretic interpretation of families of tableaux used in constructing certain functions in the peak algebra, and establish a common framework for known 0-Hecke module interpretations of bases of quasisymmetric functions.