Warm metalworking turns brittle semiconductors into flexible, high-performance electronic films

Inorganic semiconductors form the backbone of modern electronics due to their excellent physical properties, including high carrier mobility, thermal stability, and well-defined energy band structures, which enable precise control over electrical conductivity. Unfortunately, their intrinsic brittleness has traditionally required the use of costly, complex processing methods like deposition and sputtering—which apply inorganic materials to rigid substrates and limit their suitability for flexible or wearable electronics.

Now, however, a recent breakthrough by researchers from the Shanghai Institute of Ceramics of the Chinese Academy of Sciences and Shanghai Jiao Tong University in the warm processing of traditionally brittle semiconductors offers tremendous potential to expand applications for inorganic semiconductors into these fields.

In their study recently published in Nature Materials, the researchers report achieving plastic warm metalworking in a range of inorganic semiconductors traditionally considered too brittle for such processing. These findings open new avenues for efficient and cost-effective semiconductor manufacturing.

In this study, the researchers developed a model for temperature-dependent plasticity and fabricated high-performance thermoelectric devices based on warm-metalworked semiconductor films.

They found that a group of room-temperature brittle inorganic semiconductors (e.g., Cu₂Se, Ag₂Se, Bi₉₀Sb₁₀) exhibit excellent plasticity below ~200°C and thus can be easily processed using various warm metalworking techniques, such as rolling, compression, and extrusion. For instance, warm-rolled Ag₂Se semiconductor strips reached lengths of up to 90 cm, corresponding to a remarkable extensibility of approximately 3,000%.

These warm-metalworked semiconductor films offer several key advantages. They are free-standing, substrate-free, and offer tunable thicknesses ranging from micrometers to millimeters. Importantly, they retain high crystallinity and physical properties comparable to their bulk counterparts.

For instance, films of Ag₂Te, AgCuSe, and Ag₂Se with thicknesses around 5–10 μm demonstrated carrier mobilities as high as ~1,000–5,000 cm² V⁻¹ s⁻¹—approximately four times higher than that of crystalline silicon and orders of magnitude greater than most two-dimensional and organic materials.

The researchers further revealed the rich microstructures of these warm rolled or compressed materials. Dense dislocations observed in room-temperature ductile semiconductors were not widely observed in these warm-deformed samples. Moreover, the researchers developed a concise model based on temperature-dependent collective atomic displacement and thermal vibration to explain the temperature-induced superior plasticity of these materials.

By quantifying the slip barrier energy and cleavage energy, the researchers were able to construct a model that successfully predicted the brittle-to-ductile transition temperatures across various inorganic semiconductors.

To showcase the practical potential of this technique, the researchers fabricated thermoelectric devices using the warm-metalworked films. These devices delivered ultra-high normalized output power densities of 43–54 μW cm⁻² K⁻²—nearly double the performance of devices based on ductile Ag₂S semiconductors.

This study provides a transformative approach to processing brittle semiconductors, endowing them with warm metalworking capabilities and unlocking new opportunities for the scalable, low-cost fabrication of high-performance electronic and energy devices.