Pressure-Driven Reversible Switching between n- and p-Type Conduction in Chalcopyrite CuFeS₂

Abstract

Temperature-dependent switching between p- and n-type conduction is a newly observed phenomenon in very few Ag-based semiconductors, which may promote fascinating applications in modern electronics. Pressure, as an efficient external stimulus that has driven collective phenomena such as spin-crossover and Mott transition, is also expected to initialize a conduction-type switching in transition metal-based semiconductors. Herein, we report the observation of a pressure-driven dramatic switching between p- and n-type conduction in chalcopyrite CuFeS2 associated with a structural phase transition. Under compression around 8 GPa, CuFeS2 undergoes a phase transition with symmetry breakdown from space group I-42d to space group I-4 accompanying with a remarkable volume shrinkage of the FeS4 tetrahedra. A high-to-low spin-crossover of Fe2+ (S = 2 to S = 0) is manifested along with this phase transition. Instead of pressure-driven metallization, a surprising semiconductor-to-semiconductor transition is observed associated with the structural and electronic transformations. Significantly, both photocurrent and Hall coefficient measurements confirm that CuFeS2 undergoes a reversible pressure-driven p–n conduction type switching accompanying with the structural phase transition. The absence of cationic charge transfer between copper and iron during the phase transition is confirmed by both X-ray absorption near-edge spectra (Cu/Fe, K-edge) and total-fluorescence-yield X-ray absorption spectra (Fe, K-edge) results, and the valence distribution maintains Cu2+Fe2+S2 in the high-pressure phase. The observation of an abrupt pressure-driven p–n conduction type switching in a transition metal-based semiconductor paves the way to novel pressure-responsive switching devices.

Pressure‐Tailored Band Engineering for Significant Enhancements in the Photoelectric Performance of CsI3 in the Optical Communication Waveband

“…Pressure has been proven to be an effective means for tuning the photoelectronic properties of functional materials. [ 22–32 ] Significant enhancements of the photocurrent by three orders of magnitude in indirect bandgap materials Cs 2 PbI 2 Cl 2 [ 22 ] and BiO 2 S 2 [ 23 ] were realized by regulating the excitonic features and the dynamic stereochemical role of lone‐pair electrons under high pressure, respectively. In addition, direct bandgap materials are more suitable for photoelectronic applications because of their higher optical absorption coefficients compared with those of indirect bandgap materials.…”

Pressure Engineering for Extending Spectral Response Range and Enhancing Photoelectric Properties of Iodine

“…As an effective means of tuning the physical and chemical properties of materials, high pressure can be used to modify photoelectric and related properties via adjustment of the atomic and electronic structures. [19][20][21][22][23][24][25][26][27][28][29][30] Pressure-induced photoelectric performance enhancement has been achieved for several photoelectric materials, such as ReS 2 , [19] KBiFe 2 O 5 , [20] PbBiO 2 Br, [21] and Bi 9 O 7.5 S 6 . [23] However, such enhancement is typically limited.…”

Pressure-induced bandgap engineering and photoresponse enhancement of wurtzite CuInS2 nanocrystals

“…Up to now, pressure-based materials engineering has motivated and strengthened the photoelectrical performances of semiconductive halide perovskites, iodide, sulfides and oxides. 28–35 For example, the perovskite Cs 2 PbI 2 Cl 2 achieved significant photocurrent enhancement at high pressures to regulate the excitonic features. 28 The pressure-treated CH 3 NH 3 SnI 3 exhibited significantly higher photocurrent than its original phase.…”