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

Abstract

The bandgap and type of optical transition are key factors in determining the functionalities and applications of photoelectric materials. However, it is extremely difficult to modulate the bandgap and indirect‐direct bandgap transition for most materials. This study reports significant enhancements in photocurrents and an extended detection bandwidth resulting from pressure‐regulated indirect–direct bandgap transition in hypervalent CsI3. Furthermore, this study achieves an increase in the photocurrent by almost five orders of magnitude under visible‐light illumination. Impressively, the detection band‐edge shows a successive redshift from visible light to 1650 nm (optical communication waveband) upon compression. And high pressure is conducive to CsI3 operating at an ultralow bias input. Extensive high‐pressure spectroscopy analyses and theoretical calculations suggest that changes in the photoelectric properties of CsI3 are associated with enhanced I–I interactions along the quasi‐endless linear chain directions under compression. These findings offer an effective band engineering strategy for achieving broadband spectral response and high gains with an ultralow bias in photoelectric detectors.

Pressure-Induced Structural Phase Transition, Anomalous Insulator-to-Metal Transition, and n–p Conduction-Type Switching in Defective, NiAs-Type Cr1−δTe

“…In addition to the measurements of Hall and Seebeck coefficients, photocurrent measurements are also used to detect the type and concentration of carriers under HP. − The photocurrent measurement results of CrTe, Cr 3 Te 4 , and Cr 5 Te 8 are shown in Figure a–c. Below 4.3 GPa, the photocurrent amplitude of CrTe increases significantly with compression due to its rapid decrease in resistivity (Figure a).…”

High-Pressure Structures and Superconductivity of Barium Iodide

“…A large number of interesting properties of iodine compounds have been reported such as optical properties, conduction characteristics, catalytic performance, medical application and the hypervalence phenomenon [1][2][3][4][5][6][7][8][9][10]. Barium iodide (BaI 2 ), as one of the simplest and most representative ionic iodine compounds, has attracted plentiful studies [11][12][13][14][15].…”

Pressure‐Tailored Self‐Driven and Broadband Photoresponse in PbI2

“…[35] Impressively, extension of the spectral response range of CsI 3 from the visible to optical communication waveband can even be achieved. [35] Notably, PbI 2 exhibits a series of complex structural phase transitions accompanied by successive band gap Photoelectric devices based on the photothermoelectric (PTE) effect show promising prospects for broadband detection without an external power supply. However, effective strategies are still required to regulate the conversion efficiency of light to heat and electricity.…”

“…[26][27][28] As a significant external stimulus to regulate the crystal and electronic structure of materials, high pressure has been demonstrated to be a clean and effective technique for tuning photoelectricrelated properties, which enables obtainment of novel materials unobtainable under ambient conditions. [29][30][31][32][33][34][35] Recently, pressure enhancement of photocurrents by almost several orders of magnitude has been achieved in some functional materials, such as Bi 2 O 2 S, [32] Cs 2 PbI 2 Cl 2 , [33] iodine, [34] and CsI 3 . [35] Impressively, extension of the spectral response range of CsI 3 from the visible to optical communication waveband can even be achieved.…”

“…[29][30][31][32][33][34][35] Recently, pressure enhancement of photocurrents by almost several orders of magnitude has been achieved in some functional materials, such as Bi 2 O 2 S, [32] Cs 2 PbI 2 Cl 2 , [33] iodine, [34] and CsI 3 . [35] Impressively, extension of the spectral response range of CsI 3 from the visible to optical communication waveband can even be achieved. [35] Notably, PbI 2 exhibits a series of complex structural phase transitions accompanied by successive band gap Photoelectric devices based on the photothermoelectric (PTE) effect show promising prospects for broadband detection without an external power supply.…”