Achieving ultrahigh power factor in n-type Ag2Se thin films by carrier engineering

Significantly (00l)-textured Ag2Se thin films with excellent thermoelectric performance for flexible power applications

“…However, Ag 2 Se thin lms prepared by TED, originally reported by Jindal et al, 38 had a very low power factor of 7.55 mW cm −1 K −2 at 120 C. Recently, Zhang et al 39 enhanced the power factor to over 19 mW cm −1 K −2 in highly c-axis textured Ag 2 Se thin lm, suggesting that careful microstructure regulation can be a good strategy to enhance thermoelectric performance. 40 In our previous work, 41 we also used the same method to prepare exible Ag 2 Se thin lms and improved the power factor to 20.5 mW cm −1 K −2 aer carefully controlling the composition content via co-evaporated Ag and Se. However, we have found that some Ag cluster defects will easily be formed on the thin lm surface, which adversely affects its electrical transport properties.…”

Improved Power Factor in Highly Textured n-Type Ag2Se Flexible Films

“…It is further seen that both Ag 3d 5/2 and Ag 3d 3/2 peaks are asymmetrically broad, and they can be deconvoluted into two components at binding energies of 367.7 and 373.7 eV (valence: +1, corresponding to the formation of selenide) , and another at 368.6 and 374.7 eV corresponds to metallic Ag (valence: 0) . The Se 3d peak (shown in Figure c appearing at binding energies of 53.5 eV (Se 3d 5/2 ) and 54.4 eV corresponds to selenide (valence: −2). , For the sample Ag 2 Se-80 prepared with the highest thickness of the Se layer, an additional peak (other than selenide) at binding energies of 55.9 and 57 eV suggests free Se (valence: 0) in the sample . From the analysis of high-resolution Ag 3d and Se 3d XPS data of all samples, we estimated the concentrations of Ag and Se in the samples and details are shown in Table .…”

“…From Figure b, it may be seen that the Ag 3d spectra consist of two broad isolated peaks at 367.8 and 373.8 eV that correspond to the spin–orbit doublet as Ag 3d 5/2 and Ag 3d 3/2 . It is further seen that both Ag 3d 5/2 and Ag 3d 3/2 peaks are asymmetrically broad, and they can be deconvoluted into two components at binding energies of 367.7 and 373.7 eV (valence: +1, corresponding to the formation of selenide) , and another at 368.6 and 374.7 eV corresponds to metallic Ag (valence: 0) . The Se 3d peak (shown in Figure c appearing at binding energies of 53.5 eV (Se 3d 5/2 ) and 54.4 eV corresponds to selenide (valence: −2). , For the sample Ag 2 Se-80 prepared with the highest thickness of the Se layer, an additional peak (other than selenide) at binding energies of 55.9 and 57 eV suggests free Se (valence: 0) in the sample .…”

Vacuum-Deposited Cesium Tin Iodide Thin Films with Tunable Thermoelectric Properties

“…Currently, some inorganic materials, such Ag 2 Se or Cu 2 Se, have shown good prospects for room temperature applications, but a fine-tuning of the stoichiometry and deposition conditions is needed to achieve the best efficiencies, a process that can be costly and time-consuming. 12 , 13 In the search for alternative materials that are easy to process, metal halide perovskites, such as CH 3 NH 3 PbI 3 , FASnI 3 , or CsSnI 3 , have emerged in recent years as potential thermoelectric materials. Indeed, ultralow thermal conductivity and acceptable Seebeck coefficients have been demonstrated.…”

“…Hence, inorganic TE materials operating near room temperature are sought after. Currently, some inorganic materials, such Ag 2 Se or Cu 2 Se, have shown good prospects for room temperature applications, but a fine-tuning of the stoichiometry and deposition conditions is needed to achieve the best efficiencies, a process that can be costly and time-consuming. , In the search for alternative materials that are easy to process, metal halide perovskites, such as CH 3 NH 3 PbI 3 , FASnI 3 , or CsSnI 3 , have emerged in recent years as potential thermoelectric materials. Indeed, ultralow thermal conductivity and acceptable Seebeck coefficients have been demonstrated. − Sn-based halide perovskites surpass their Pb counterparts in thermoelectric performance because of the self-oxidation of Sn 2+ to Sn 4+ , acting as a self-doping mechanism that enhances their electrical conductivity .…”