Abstract
Lead-free thermoelectric material, copper chalcogenides, have been attracting much interest from many research and industrial applications owing to their high capability of harvesting energy from heat. The state-of-the-art copper chalcogenides are commonly fabricated by the spark plasma sintering (SPS) and hot pressing (HP) techniques. Those methods are still costly and complicated particularly when compared to the conventional solid-state sintering method. Here, we report an easy-to-fabricate lead-free copper(I)-selenium (Cu2Se) that was fabricated using the conventional sintering method. The fabrication conditions, including sintering temperature and dwelling time, have been systematically studied to optimize the thermoelectric performance of Cu2Se. The optimized zT value for the pure Cu2Se was found to be 1.2 for the sample sintered at 1173 K for 2 h. The study shows that Cu2Se developed using the simple and low-cost techniques could exhibit comparable thermoelectric performance when compared with those fabricated by the SPS method, which provides an alternative potential technique to synthesize high-performance thermoelectric materials in a cost-effective way for industrialization.
Highlights
Thermoelectric material defines one kind of material specified by the capability of converting heat into electricity directly and vice versa [1,2]
Among the state-of-the-art excellent thermoelectric materials, copper selenide (Cu2 Se) has been widely studied due to its potential of having high zT and its environmentally friendly nature when compared with lead-based thermoelectric materials
S. et al, employed the melt-quenching method to obtain a mixture of β-Cu2Se (PDF card number: 46-1129) and α-Cu2 Se (PDF card number: 19-0401)
Summary
Thermoelectric material defines one kind of material specified by the capability of converting heat into electricity directly and vice versa [1,2]. Attempts to resolve the issue include introducing a second phase-like CuInSe2 [12] and enlarging the band gap by the substitution of Cu sites with Li [13] or other dopants such as Sn [14] Another strategy proposed is to use a blocking layer like carbon to suppress the migration of Cu under high current flow inside the material [15]. The superionic nature of Cu2 Se allows Cu to migrate under the high current flow, which is the case during the sintering progress using the SPS technique. This kind of Cu migration in the SPS process has been observed by G. The optimized zT value approached 1.2 at 823 K for the samples sintered at 1173 K for two hours
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