This doctoral dissertation aims to enhance the critical current density (Jc) of high-temperature superconductors (HTS) based on YBa2Cu3O7−δ (YBCO) to maximize their potential. Achieving high Jc in superconductors involves balancing the impact of crystalline perfection on self-field critical current density, Jc(0), and the influence of artificial pinning centers (APCs) on in-field critical current density, Jc(B). The study explores the intricate balance between maximizing pinning efficiency through higher APC density and enhancing crystalline quality in YBCO to optimize Jc (0) and Jc (B). The research aims to find the optimal strain level to stabilize conflicting requirements in APC/YBCO nanocomposite films. Investigations include BaZrO3 (BZO)-doped YBCO thin films on miscut SrTiO3 (STO) substrates, revealing the influence of modified strain produced by the substrate on YBCO and BZO nanorod growth and their impact on critical current densities. The study then extends to superconducting multilayer structures, examining alternating YBCO films doped with different BZO nanocolumn densities and heteromultilayer structures. Experimental outcomes reveal the interplay of crystalline quality and flux pinning, emphasizing the potential of demonstrated multilayer structures to address challenges in achieving optimal Jc for future HTS power applications.