A novel strategy for the preparation of extremely thick composites by photochemical and/or thermal free radical polymerization (FRP) and/or cationic polymerization (CP) under low-energy consumption visible light emitted diodes (LEDs) is described. The approach is based on the use of charge transfer complexes (CTCs) formed between N-aromatic amines (donors) and iodonium salts (Tod, acceptors). Remarkably, it is demonstrated for the first time that these CTCs can be used as thermal initiators for free radical polymerization (FRP) initiation with performances comparable to dibenzoyl peroxide-based systems. The decomposition temperature of these CTC thermal initiators can be modulated through the selection the amine, providing much safer conditions for synthesis, storage, and handling than that of the classical thermal initiators. A good stability in resin is also noted.