Finding a more flexible mechanical sensor: Piezoelectric materials allow conversion between electricity and mechanical stresses. The most efficient piezoelectric materials are ceramics such as BaTiO ₃ or PbZrO ₃ , which are also extremely stiff. You et al. identified an organic perovskite structured piezoelectric material that is far more pliable yet has a piezoelectric response similar to that of traditional ceramics. This material may be a better option to use as a mechanical sensor for flexible devices, soft robotics, biomedical devices, and other micromechanical applications that benefit from a less stiff piezoelectric material. Science , this issue p. 306

Inorganic semiconductor ferroelectrics such as BiFeO₃ have shown great potential in photovoltaic and other applications. Currently, semiconducting properties and the corresponding application in optoelectronic devices of hybrid organo-plumbate or stannate are a hot topic of academic research; more and more of such hybrids have been synthesized. Structurally, these hybrids are suitable for exploration of ferroelectricity. Therefore, the design of molecular ferroelectric semiconductors based on these hybrids provides a possibility to obtain new or high-performance semiconductor ferroelectrics. Here we investigated Pb-layered perovskites, and found the layer perovskite (benzylammonium)₂PbCl₄ is ferroelectric with semiconducting behaviours. It has a larger ferroelectric spontaneous polarization P_s=13 μC cm⁻² and a higher Curie temperature T_c=438 K with a band gap of 3.65 eV. This finding throws light on the new properties of the hybrid organo-plumbate or stannate compounds and provides a new way to develop new semiconductor ferroelectrics.

A flexible strategy for piezoelectrics: Piezoelectric materials produce charge when they are deformed, making them ideal for various types of sensors. However, virtually all piezoelectric materials are ceramics, which are far from ideal for applications requiring flexible sensors. Liao et al. now describe a molecular material with piezoelectric properties comparable to the industry-standard ceramic lead zirconate titanate. The exceptional properties come from finding a molecular solid-solution series that allows for compositional optimization of the piezoelectric properties. Science , this issue p. 1206