Exceptionally high work density of a ferroelectric dynamic organic crystal around room temperature

Dynamic organic crystals are rapidly gaining traction as a new class of smart materials for energy conversion, however, they are only capable of very small strokes (<12%) and most of them operate through energetically cost-prohibitive processes at high temperatures. We report on the exceptional performance of an organic actuating material with exceedingly large stroke that can reversibly convert energy into work around room temperature. When transitioning at 295-305 K on heating and at 265-275 K on cooling the ferroelectric crystals of guanidinium nitrate exert a linear stroke of 51%, the highest value observed with a reversible operation of an organic single crystal actuator. Their maximum force density is higher than electric cylinders, ceramic piezoactuators, and electrostatic actuators, and their work capacity is close to that of thermal actuators. This work demonstrates the hitherto untapped potential of ionic organic crystals for applications such as light-weight capacitors, dielectrics, ferroelectric tunnel junctions, and thermistors. Organic electronics requires dynamic materials, however, most of them have small strokes and operate at high temperatures. Here, the authors describe organic crystal that repeatedly expands and contracts nearly half its length around room temperature.

Automated summary

This study reports on an organic actuating material with exceptionally large stroke that can convert energy into work at room temperature. The material outperforms electric cylinders, ceramic piezoactuators, and electrostatic actuators in terms of maximum force density and has work capacity comparable to thermal actuators. The study demonstrates the untapped potential of ionic organic crystals for various applications.