Photothermally Enhanced Photoresponse of Bismuth Halide Perovskite by Phonon Scattering

Abstract

Controlling the thermal conductivity of metal halide perovskites is of significance to promising applications ranging from optoelectronic devices to heat storage and conversion devices. Herein, we carry out the thermal management of bismuth halide perovskite. As measured by time-domain thermo-reflectance, the Cs3Bi2I9 thin film possesses a thermal conductivity of 0.15 W m–1 K–1 that is lower than that of the BiI3 thin film with a thermal conductivity of 0.31 W m–1 K–1. We attribute the differential thermal conductivity to the stronger phonon scattering of Cs3Bi2I9 at low frequencies as compared to that of BiI3. In addition, we fabricated photothermal detectors by employing BiI3 and Cs3Bi2I9 thin films with different heat transport characteristics. As a result, the detectors using Cs3Bi2I9 have a larger response temperature, stronger photocurrent, higher responsivity, and normalized detectivity than the detectors using BiI3. The unique heat transport characteristics provide a prospect for photothermal detection. Furthermore, the insights in this report imply opportunities to explore ultra-low thermal conductivity among metal halide perovskites.

Nature‐Inspired Halide Perovskite Breath Figures: Unleashing Enhanced Light‐Matter Interaction

“…Compared to solution-processed A 3 B 2 I 9 (A = Cs, MA, and B = Bi, Sb) thin film-based photodetectors (Figure 7b; Table S3, Supporting Information), the MA 3 Bi 2 I 9 BFs exhibit a remarkably higher responsivity and detectivity. [39,[51][52][53][54][55][56][57][58][59] This sets a new standard for photoresponse performance among thin film A 3 B 2 I 9 -based photodetectors.…”

Low-Temperature Heat Capacity of CsPbI3, Cs4PbI6, and Cs3Bi2I9

“…Between 2004 and 2010, a series of studies into the optical behavior of the low-temperature phase of Cs 3 Bi 2 I 9 were furthermore reported by Motsnyi et al − Electron–phonon coupling was studied, as well as exciton–phonon coupling. , Exciton–phonon interaction resulted in the disappearance of the layered structure below the transition temperature. Phonon calculations using VASP were performed by Geng et al Until recently, no report on the low-temperature heat capacity of Cs 3 Bi 2 I 9 had been published, apart from statements on an undetectable anomaly or very small latent heat by Melnikova et al The recent work by Tailor and Satapathi is the first report of a heat capacity curve. The even more recent work by Acharyya et al measured the heat capacity only up to 50 K. The discrepancy with respect to our own results for the electronic contribution was already discussed supra.…”

“…Their attempt to explain their results refers to research into thermal conductivity. Cs 3 Bi 2 I 9 is known to have a very low thermal conductivity (0.15 W·m –1 ·K –1 as measured on thin films) 12 and cautiousness is necessary in measuring the heat capacity of insulating materials. 71 When performing QD-PPMS measurements by the thermal-relaxation technique, caution should be taken with regard to the sample mass: for materials with a very low thermal conductivity, lower mass results in more accurate measurements; sample mass can affect the results already above quantities as small as 15 mg. 46 No mass of the crystal is given in the work of Tailor and Satapathi, 54 but based on the picture in their Supporting Information , the sample is estimated to be between 7 and 30 mg, so it is not clear to us whether the mass might play a role.…”

“…Cs 4 PbI 6 is the lesser investigated salt in the CsI–PbI 2 system. − In their review of metal halide perovskites, Kovalenko et al describe the huge increase in publications in the field in the past decade. Despite the attention these materials are getting, studies of their low-temperature behavior seem to be rather limited and originate mainly from luminescence and scintillation-related studies. ,, Other works include the investigation of thermal transport properties, reporting (ultra)­low thermal conductivity for Cs 3 Bi 2 I 9 and CsPbI 3 . − …”

“… 7 , 10 , 11 Other works include the investigation of thermal transport properties, reporting (ultra)low thermal conductivity for Cs 3 Bi 2 I 9 and CsPbI 3 . 12 − 16 …”