Electrodeposition of Dense Lead Telluride Thick Films in Alkaline Solutions

Abstract

Dense PbTe thick films were electrodeposited in alkaline solutions by an underpotential deposition mechanism of Pb on overpotential deposited Te. The composition of Pb is critical for the material properties. The composition of the electrodeposited PbTe films was Te-rich. Although the applied potential had no substantial effect on the Pb composition, it needs to be in the proper range (from −0.8 to −1.1 V vs. sat. Ag/AgCl) to avoid further reduction of Te to Te 2 2− or keep the reduction of Te to Te 2 2− at a low reaction rate. To deposit dense thick films the pH must be maintained in the range 10.5 to 12.3. Higher TeO 3 2− concentrations and lower pH values decreased the Pb composition but increased deposition rates. Varying the TeO 3 2− concentration changed the surface morphology of thick PbTe films, but all the thick films were found to be dense in the SEM cross section images. The ratio of EDTA 4− /Pb 2+ is also a critical effect, and the data showed that 7.5 was the optimum ratio with the given conditions, where the electrodeposited PbTe film was dense without cracks. A high deposition rate (approx. 163 μm/h) was achieved by high TeO 3 2− concentrations (i.e., 550 mM) and at the deposition potential of 1.05 V vs sat. Ag/AgCl. The as-deposited PbTe films have relatively high Seebeck coefficient (i.e., 524 μV/K), but low electrical conductivity compared to bulk counterpart which might be attributed to lower crystallinity of PbTe with embedded Te nanocrystals.

Development of Perovskite-Type Materials for Thermoelectric Application

“…Moreover, TE devices have advantages of no vibration, no noise, and highly reliable because they are solid-state devices without moving parts. In our previous studies, thick thermoelectric tellurium (Te) [19] and lead telluride (PbTe) [20] films were synthesized by electrodeposition with high film growth rate. The combination of electrochemical deposition of compound semiconductors with standard integrated circuit technique enables the fabrication of thermoelectric microdevices, which has a more compact size and a capability to handle a wider range of thermal and power management [21,22,23].…”

“…Materials such as organic [5,6,24,25,26,27,28,29,30,31,32], hybrid perovskites [33,34,35] and the group V chalcogenides [3,7,10,11,12,36] are suitable for TE application at the near-room-temperature range. In addition, TE materials—such as the group IV chalcogenides [10,11,20,36], group III-V compounds [10,17,36], group IV-based materials [7,10,12,36], half-Heusler alloys [3,7,9,11], skutterudites [3,11,37], Zintl compounds [3,9,12,37], and clathrates [9,11]—are applicable at the middle temperature (about 400–900 K) range. Furthermore, materials—like rare earth chalcogenides [36], oxide perovskites [38,39,40], borides [36], and metal oxides [36]—can be used at a high temperature (>1000 K) range.…”

“…The inorganic materials are the most well-studied TE materials [3,7,10,11,12,36,41]. We have studied the thermoelectric properties of PbTe films [20] and silver telluride nanofibers [41]. Additionally, Te nanostructures including nanowire [42], nanotree [42], and nanorice [43] were synthesized, which can be used to be embedded into other TE materials as nanocomposite [44,45,46] or converted to metal tellurides through cation exchange reaction [47,48].…”

Micro thermoelectric devices: From principles to innovative applications

“…[34] In contrast, electrodeposition is a cost-effective and high throughput method to synthesize high-aspect-ratio thermoelectric thin film and compatible with microfabrication processes. [35][36][37] Moreover, electrodeposition can fabricate films on large and irregular surfaces, which provides the foundation of material synthesis for the broad applicability of µ-TEDs.…”

Reconstruction of Lead Acid Battery Negative Electrodes after Hard Sulfation Using Controlled Chelation Chemistry

“…33,36 Reduction of the Pb-EDTA chelates can form uniform metal films and the EDTA molecules can be reused for further binding. 33,[37][38][39] However, these films are generally not tested as a battery material. Thus, we posited that chelators could be used in a two-step process involving: (1) removal of large, inactive PbSO 4 crystals to reactivate damaged electrodes and (2) electrodeposition of fresh electrode material from the Pb-chelator solution (Scheme 1).…”