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Perovskite/silicon tandem solar cells (TSCs) have aroused much attentions in recent years. One of keys for achieving highly efficient and stable TSCs is to guarantee effective charge transfer, especially on the rough textured silicon substrate due to the poor adhesion between interlayers. Here, a 2‐fluoroisonicotinic acid (2‐FNA) additive that possesses fluorine (‐F), carboxylic acid (‐COOH), and pyridine nitrogen as functional groups in the perovskite precursor to assist the crystallization process is utilized. It shows that 2‐FNA can efficiently reduce the defects and suppress non‐radiative recombination of perovskite layers by bonding with the uncoordinated Pb2+ ions, formamidinium (FA+), and halide vacancies, leading to notably prolonged carrier lifetime. Most importantly, this found that 2‐FNA aids in the formation of better interfacial contact between the perovskite and C60 layer on top, thus enhancing the interfacial electron extraction therein, eventually leading to an increased power conversion efficiency (PCE) of 28.61% on champion perovskite/silicon TSCs from 27.08% on control counterparts. This work provides a practical route to further advance the PV performance and applicability of perovskite/silicon TSCs. [ABSTRACT FROM AUTHOR]

Most achievements on remarkable thermoelectric performance have been made in the intermediate-temperature p-type PbTe. However, the n-type PbTe exhibits a relatively poor figure of merit ZT, which is urgently expected to be enhanced and compatible with the p-type counterpart. Here, we report that the introduction of excessive Pb can effectively eliminate cation vacancies in the n-type Pb 1 + x Te − 0.4 % I , leading to a considerable improvement of carrier mobility μ. Moreover, further Ge doping induces a large enhancement of thermoelectric properties due to the combined effect of improved electrical transport properties and increased phonon scattering in the n-type Pb 1.01 Te − 0.4 % I − y % Ge. The Ge doping not only contributes to the increase of the Seebeck coefficient owing to the increased effective mass m ∗ , but also gives rise to the dramatic decrease of lattice thermal conductivity due to the strengthened point defects scattering. As a result, a tremendous enhancement of the ZT value at 723 K reaches ∼ 1.31 of Pb 1.01 Te − 0.4 % I − 3 % Ge. Particularly, the average Z T a v e value of ∼ 0.87 and calculated conversion efficiency η ∼ 13.5 % is achieved by Ge doping in a wide temperature range from 323 to 823 K. The present findings demonstrate the great potential in the n-type Pb 1.01 Te − 0.4 % I − y % Ge through a synergistic tuning of carrier mobility, effective mass, and point defects engineering strategy. [ABSTRACT FROM AUTHOR]

Direct ink writing offers a unique solution for constructing shape-controllable devices. In this way, thermoelectric (TE) devices can optimize power generation from industrial waste heat by the design of structural parameters. Despite recent interest in the so-called all-inorganic inks with inorganic binders to engineer viscoelasticity, organic impurities may also be triggered by high portion of organic solvents, which hamper the electron and phonon transport. Herein, we report water-based inks to reduce organic residuals. The quasi-inorganic inks were synthesized by adding Bi2Te3-based particles to water solvent with a few organic binders, whose total organic content is less than that of all-inorganic inks. Moreover, an interface-solder approach is employed to fill the pores among grain particles with the liquefied phase. As a result, there is a tremendous enhancement of ZT values, reaching 0.71 and 0.59 for 3D-printed p- and n-type Bi2Te3-based TE materials, respectively. In particular, the flexible method promotes the realization of waste heat harvesting from an alumina pipe by fabricating a TE module integrated with printed half-annular legs. Our work demonstrates not only the effectiveness of quasi-inorganic inks and interface engineering as a means of increasing ZT values, but also the great potential of 3D-printed Bi2Te3-based TEGs for waste heat recovery. [ABSTRACT FROM AUTHOR]

Understanding the alloying effect is of critical significance for rationally designing highly efficient thermoelectric materials. Here, we report that a Co- and Cu-substituted alloying effect in misfit-layered (SnS)1.2(TiS2)2 can directly enhance the thermoelectric performance with the highest dimensionless figure of merit ZT of ∼ 0.42 at 720 K until now. The substitution of Co3+ and Cu2+ for Ti4+ ions reduces the electron carrier concentration of the n-type material, thereby contributing to the increase of the Seebeck coefficient, which is clearly evidenced by the Hall measurement. In addition, the introduction of point defects due to the Co and Cu substitution gives rise to the decrease of phononic thermal conductivity. Consequently, the Co- and Cu-substituted alloying effect triggers an optimized carrier concentration, local mass fluctuation, and local strain variation, which inherently lead to the enhancement of thermoelectric properties owing to the combined effect of improved electrical transport properties and increased phonon scattering. The present misfit-layered chalcogenide provides an excellent platform for modulating the thermoelectric performance via an element-substituted alloying effect. [ABSTRACT FROM AUTHOR]

High-energy-conversion Bi 2 Te 3 -based thermoelectric generators (TEGs) are needed to ensure that the assembled material has a high value of average figure of merit ( ZT ave ). However, the inferior ZT ave of the n-type leg severely restricts the large-scale applications of Bi 2 Te 3 -based TEGs. In this study, we achieved and reported a high peak ZT (1.33) of three-dimensional (3D)-printing n-type Bi 2 Te 2.7 Se 0.3 . In addition, a superior ZT ave of 1.23 at a temperature ranging from 300 to 500 K was achieved. The high value of ZT ave was obtained by synergistically optimizing the electronic- and phonon-transport properties using the 3D-printing-driven defect engineering. The nonequilibrium solidification mechanism facilitated the multiscale defects formed during the 3D-printed process. Among the defects formed, the nanotwins triggered the energy-filtering effect, thus enhancing the Seebeck coefficient at a temperature range of 300-500 K. The effective scattering of wide-frequency phonons by multiscale defects reduced the lattice thermal conductivity close to the theoretical minimum of ∼0.35 W m -1 k -1 . Given the advantages of 3D printing in freeform device shapes, we assembled and measured bionic honeycomb-shaped single-leg TEGs, exhibiting a record-high energy conversion efficiency (10.2%). This work demonstrates the great potential of defect engineering driven by selective laser melting 3D-printing technology for the rational design of advanced n-type Bi 2 Te 2.7 Se 0.3 thermoelectric material.