weighted by cyclical constrains. Furthermore, the approach proposed by Schumpeter embodies another fundamental idea, which is the competition between innovators. Indeed, these players pursue the monopoly rents that accrue to new proprietary technologies, and, as such, intend to be the fi rst to fi nd the right solution to the right problem at the right moment. Economists have been studying the relationship between innovation and competition for many years, trying to understand more specifi cally whether competition fosters innovation or not. As a matter of fact, some concluded on a negative infl uence of competition upon innovation and some on a positive effect. [ 2,5 ] But it appears that many economists and marketers converge toward the idea that the innovation versus competition curve shows an inverted U shape. [ 6 ] In other words some competition is constructive, yet aggressive competition tends to hamper the innovation process.It is interesting to place in this context the concept of duplication. Historians and sociologist often refer to multiple discoveries for cases in which similar discoveries are made simultaneously by scientists working independently from each other. [ 7 ] The wide literature of scientifi c discovery can be classifi ed into three basic categories: [ 8 ] the genius model, [ 9 ] the model based on chance, [ 10 ] and the model relying on cultural maturation. [ 11 ] The latter type, which is the more prone to multiplicity, suggests that the contributions of individual researcher are epiphenomenal. This school of thought advocates the infl uence of social determinism and zeitgeist. [ 12 ] As a consequence, it proposes that the change in science is strongly infl uenced by cultural priorities and research programs. [ 8 ] This very type of duplication can be considered benefi cial for society as a higher number of independent experiments does maximize the probability of the accuracy and the reality of a given discovery. [ 11 ] This point of view is easily applicable to paradigm shifting, major discoveries, especially if they occurred before the era of easily accessible information via the internet, gigantic centralized databases, and ultrafast search engines. However, nowadays it may appear obvious that the replication of the effort to generate innovation is socially suboptimal and reduces the overall return on investment for entities that fi nance research. None of the studies mentioned above accounts for that phenomenon because of the diffi culty to quantify modern duplication. Thus, despite its acknowledged relevance [ 13 ] and occurrence, the share and infl uence of modern duplication in academic and industrial research remains largely underexplored. The European Patent Offi ce (EPO) affi rms that "up to 30% of all expenditure in R&D is wasted on redeveloping existing Copper sulfi des and copper selenides have recently been reported as new and promising low-cost and environmentally friendly thermoelectric materials. Here, it is shown that these materials have actually been studied for mo...

Accelerating the discovery of new materials is crucial for realizing the vision of need-driven materials development. In the present study we employ an integrated computational and experimental approach to search for new thermoelectric materials. High-throughput first principles calculations of thermoelectric transport coefficients are used to screen sulfide compounds conforming to the boundary conditions of abundant and innocuous components. A further computational screening step of substitutional defects is introduced, whereby SnS doped with monovalent cations is identified as having favorable transport properties. By silver doping of SnS under S-rich conditions an electric conductivity more than an order of magnitude higher than reported previously is realized. The obtained thermoelectric power-factor at room temperature is comparable to the state of the art for thermoelectric materials based on earth abundant, non-toxic elements. The high-throughput screening of extrinsic defects solves a long standing bottleneck in search of new thermoelectric materials. We show how the intrinsic carrier concentration in the low-temperature phase of SnSe is two orders of magnitude higher than in SnS. We furthermore find that the carrier concentration in SnSe can still be further optimized by silver doping.

Electronic and transport properties of Bi2S3 with various dopants are studied using density functional theory and experimental characterizations. First, principle calculations of thermoelectric properties are used to evaluate the thermoelectric potential of the orthorhombic Bi2S3 structure. The computational screening of extrinsic defects is used to select the most favorable n-type dopants. Among all the dopants considered, hafnium and chlorine are identified as prospective dopants, whereas, e.g., germanium is found to be unfavorable. This is confirmed by experiment. Seebeck coefficient (S) and electrical conductivity (σ) measurements are performed at room temperature on pellets obtained by spark plasma sintering. An increase of power factors (S2·σ) from around 50 up to 500 μW K−2 m−1 is observed for differently doped compounds. In several series of samples, we observed an optimum of power factor above 500 μW K−2 m−1 at room temperature for a chlorine equivalence of 0.25 mol. % BiCl3. The obtained results are plotted on a semilogarithmic log (σ) versus S graph to demonstrate that a very strong linear trend that limits the power factor around 500 μW K−2 m−1 exists. Further improvement of Bi2S3 as thermoelectric material will require finding new doping modes that will break through the observed trend. The results of stability tests demonstrate that properties of optimally doped Bi2S3 are stable.

Paracostibite (CoSbS) has recently been identified as a promising thermoelectric material, yet its full potential remains to be attained. By carrying out an optimization of the experimental parameters, we achieve a power factor as high as 2.7 mW m−1 K−2 at 543 K.