Abstract A full spectroscopic characterisation of triplet miniclusters of N- h 8 in a crystai of N- d 8 and their interactions via the lattice states is presented in a two-dimensional lattice. Triplet mini-exciton energy levels, transition moments and polarisations are calculated. A randon trial model is used to calculate the effective (spectroscopic) concentration of the different clusters and their topology (spatial distribution and orientation in a two-dimensional 100 × 100 lattice, Spectra, and cluster—cluster couplings leading to transfer or exciton fusion are calculated for local concentrations. It is shown that the average concentration is a very poor parameter for predicting cluster-cluster interactions or cluster spectra lineshapes. The knowledge of inhomogeneity of traps is also important when direct excitation of triplet traps is performed.