<p>The field of piezotronics and piezo-phototronics has made remarkable advancements since the previous <i>MRS Bulletin</i> on piezotronics was published in 2018, building upon the foundational work initiated by Z.L. Wang in 2007. Researchers have made significant strides in leveraging piezoelectric semiconductors to manipulate charges and electric fields in various devices, such as ultrasensitive piezotronic sensors and self-powering systems (Figure&#xa0;1). Recent studies in the field have focused on 1D semiconductors such as ZnO and GaN, and 2D semiconductors such as MoS₂ and WSe₂, which exhibit noncentrosymmetric crystal structures essential for piezotronic functionality. Progress in fundamental understanding and device fabrication has broadened the scope of applications, including more sophisticated logic computations, chemical sensing, enhanced optoelectronics, and advanced tactile imaging. Moreover, the expansion into piezo-phototronics has unveiled new possibilities by exploring the synergistic effects of the mechanical, piezoelectric, and optical interactions in piezoelectric semiconductors. This has enabled the creation of high-performance solar cells, photodetectors, light-emitting diodes, and other optoelectronic devices with enhanced strain-engineered performances, pushing the boundaries of what these technologies can achieve. The recently discovered flexoelectronic effect further expands the strain gating of charge carriers even in centrosymmetric semiconductors such as silicon, allowing for the implementation of high-performance electrochemical applications leveraging state-of-the-art semiconductor technologies. We have seen rapid growth in the research of piezotronics and piezo-phototronics worldwide (Figure&#xa0;2). The articles in this issue highlight recent progress in piezotronics and piezo-phototronics, and this introductory article places them into perspective.</p> Graphical abstract <p></p>