Heterogeneous Integration of Chiral Lead–Chloride Perovskite Crystals with Si Wafer for Boosted Circularly Polarized Light Detection in Solar‐Blind Ultraviolet Region

Abstract

source in quantum optics, magnetic memory devices, and high-definition imaging. [4][5][6][7] For those CPL-based devices it is necessary to distinguish between two polarization states of CPL, that is, to establish sensitive CPL detectors. Different from the indirect method of detecting CPL, chiral material can enable direct CPL detectors without the assistance of optical elements, meeting the demands for integrated and flexible devices.One of the grand challenges for direct CPL detectors is seeking suitable chiral materials with excellent semiconductor properties and strong chiroptical activity. [8] In this regard, chiral hybrid organic-inorganic perovskites (HOIPs) are especially promising. [9] They are typically formed with nanometer-thick inorganic [PbX 6 ] 4− (X = Cl, Br, I) octahedral framework and separated one from another by barriers of chiral organic ligands. [10][11][12] This structural feature can induce chirality into inorganic sublattice band edge states, allowing efficient charge transport and at the same time, chiroptical activity of these hybrid materials. [13][14][15][16][17] So far, prominent CPL photodetectors based on chiral HOIPs have been achieved (e.g., [(R)-NEA]PbI 3 , [(R)-MPA] 2 MAPb 2 I 7 , [(R)-/(S)-MBA]PbI 4 , and [(R)-/(S)-PEA]PbI 3 ), fully revealing their promise in this field. [18][19][20][21][22] Despite such an advance, however, those presented devices are characterized only at wavelengths in visible bands and typically achieve anisotropy factor of less than 0.2. Sensitive chiral HOIP detectors that target Chiral hybrid organic-inorganic perovskites (HOIPs) have been well developed for circularly polarized light (CPL) detection, while new members that target at solar-blind ultraviolet (UV) region remain completely unexplored.Here, an effective design strategy to demonstrate circular polarization-sensitive solar-blind UV photodetection by growing wide-bandgap chiral HOIP [(R)-MPA] 2 PbCl 4 ((R)-MPA = methylphenethylammonium) single crystals onto silicon wafers, with well-defined heterostructures, is reported. The solid mechanical and electrical connection between the chiral HOIP and silicon wafer results in strong built-in electric field at heterojunction, providing a desirable driving force for separating/transporting carriers generated under CPL excitation at 266 nm. Unexpectedly, during such a transport process, not only the chirality of HOIP crystal is transferred to the heterostructure, but also the circular polarization sensitivity is significantly amplified. Consequently, anisotropy factor of the resultant detectors can reach up to 0.4 at zero bias, which is much higher than that of the pristine single-phase chiral HOIP (≈0.1), reaching the highest among the reported CPL-UV photodetectors. As far as we know, the integration of chiral HOIP crystals with silicon technology is unprecedent, which paves a way for designing boosted-performance CPL detectors in solar-blind UV region as well as for other advanced optoelectronic devices.

Magnetic Doping Induced Strong Circularly Polarized Light Emission and Detection in 2D Layered Halide Perovskite

“…The findings indicate that the performance of our Co 2+ -doped (PEA) 2 PbI 4 device is superior to the reported results in systems similar to those of CPL detectors. [30,43] detector indicates that magnetic metal doping induces a long spin relaxation lifetime of the spin electrons generated by the absorption of σillumination, [27] which is consistent with the result of CPL absorption in Figure 5b. The selectivity for CPL detection in our devices was further confirmed by the optical switching characteristics (Figure 5d,e), which also revealed superior good stability and reversibility of our devices.…”

Spin-polarized excitons and charge carriers in chiral metal halide semiconductors

“…Spin polarized excitons are separated by a built-in electric field originating from the heterojunction in the photodiode architecture. 82,84 As a low-dimensional metal halide semiconductor, a CMHS has a large exciton binding energy, which leads to a high exciton recombination rate and difficulty in the separation of photogenerated charges. Recently, it was found that a CMHS-based heterojunction has interlayer exciton coupling 85 and controlled valley polarization.…”

“…86 A heterojunction based CPD combined a built-in electric field and CISS effect, which is expected to show a higher resolution of circularly polarized light. The ( R -MPA) 2 PbCl 4 /Si heterojunction 82 has a defect density of states (3.9 ± 2.2) × 10 10 cm −3 comparable to that of the ( R -MPA) 2 PbCl 4 single crystal ((2.0 ± 1.8) × 10 10 cm −3 ), and has a shorter PL lifetime (3.2 ns) than the ( R -MPA) 2 PbCl 4 single crystal, indicating that the ( R -MPA) 2 PbCl 4 /Si heterojunction has a lower spin-polarized exciton recombination rate. In the CPD based on ( R -MPA) 2 PbCl 4 /Si (the device structure in Fig.…”

Circularly Polarized Light Detection by Chiral Photonic Cellulose Nanocrystal with ZnO Photoconductive Layer in Ultraviolet Region

“…Unlike indirect detection which requires optical elements, direct detection of CPL by chiral materials with intrinsic advantages can be exploited for integration in more applications [9]. Directly detectable electronic circuits for CPL can be created by a heterojunction photodiode [10][11][12], field-effect transistor [9], and plasmon resonance [13] to distinguish between different polarization states of CPL. Chiral organic semiconductors can be integrated as the photoactive layer in bulk heterojunction photodiodes to convert CPL into a polarization-dependent photocurrent [10,14].…”

“…Chiral organic semiconductors can be integrated as the photoactive layer in bulk heterojunction photodiodes to convert CPL into a polarization-dependent photocurrent [10,14]. Chiral hybrid organic-inorganic perovskites induce chirality into inorganic sublattice band edge states for efficient charge transport [11]. Chiral metamaterials based on plasmonic elements generate photocurrent from hot carrier generation and injection [13].…”