NOVELTY - Polymer structure having a hole conducting layer and electron conducting layer including first or second hyperbranched polymers.    USE - The functional element is used as a light-emitting element, display, solar cell, photoelectric converters, organic FET elements, capacitors, sensor elements, light modulation elements, and rectification elements.    ADVANTAGE - Reliability and properties of the functional element are improved. The transistor has a similar level of characteristics as a alpha-Si TFT.    DETAILED DESCRIPTION - Polymer structure has a hole conducting layer and an electron conducting layer. The polymer structure has a first hyper-branched polymer and a second hyper-branched polymer and at least1 of these has hole conductivity or electron conductivity. At least one of the hole conducting layer and the electron conducting layer comprises one of the first hyper-branched polymer and the second hyper-branched polymer. The polymer structure has a self-assembled structure formed by a non-covalent bond interaction via the first hyper-branched polymer and the second hyper-branched polymer in at least1 of the hole conduction layer, electron conduction layer or between these layers.    INDEPENDENT CLAIMS are also included for:    (1) a functional element which has the polymer structure and electrodes which electrically contact with the structure;    (2) a transistor which has a semiconductor layer between the first and second electrodes and a third electrode for applying an electric field to the semiconductor layer containing a hyper-branched polymer and having a self-assembled structure formed by a non-covalent bond interaction via the hyper-branched polymer; and    (3) a display device having many pixels and active elements opposed to the pixels where the active elements are the transistors.    DESCRIPTION OF DRAWING(S) - Figure 5 shows a functional element.    Electrode (1)    Electron conduction layer (2)    Electron conduction layer (3)    Electrode (4)    Hole conduction layer (5)    Hole conduction layer (6)    Light emitting layer (7)    Charge generating layer (8)