Zinc oxide (ZnO) possesses a long history. It was initially predicted to be used in the fields of piezoelectrics and nonlinear optics because of its non-centrosymmetric microstructure. And it is an important wide-bandgap semiconductor material that has received extensive attention in the semiconductor field due to its direct wide band gap (Eg~3.3 eV at 300 K) and large exciton binding energy (~60 meV). However, in practical applications, ZnO has encountered some bottlenecks in all above-mentioned fields. For example, in the field of piezoelectrics, ZnO was originally thought to be an insulator, but it shows unexpected conductivity. In the field of nonlinear optics, the refractive index difference of ZnO is very poor, so it is difficult to obtain good phase matching. In the field of semiconductor, it is difficult to obtain p-type ZnO with high carrier concentration, high mobility, and high thermal stability at the same time. This article mainly summarizes the application prospects and corresponding bottlenecks of ZnO in the above-mentioned fields. And a theory that can be understood by both semiconductor physicists and materials scientists is proposed. Specifically, chemical composition complete expression (CCCE) uniquely determines the conduction type of materials. As a novel knowledge, this connects the two concepts of CCCE and carrier type, which makes a great breakthrough in understanding and forms a new paradigm for materials science research. Under this guidance, n-type ZnO single crystals with high insulation and high thermal stability, Al∶ZnO thin films with high mobility were successfully manufactured. And it provides a new idea for the preparation of p-type ZnO with high carrier concentration, high mobility and high thermal stability. Recently, the native ZnO bulk crystal has been found to have a new possibility of breaking the bottleneck of MIR transparent conductivity. ZnO∶Ga crystal scintillators are also identified as promising ultrafast inorganic scintillators. It is speculated that these two fields would achieve progress in practical applications.