Antimony selenide (Sb2Se3) has a one-dimensional (1D) crystal structure comprising of covalently bonded (Sb4Se6)n ribbons stacking together through van der Waals force. This special structure results in anisotropic optical and electrical properties. Currently, the photovoltaic device performance is dominated by the grain orientation in the Sb2Se3 thin film absorbers. Effective approaches to enhance the carrier collection and overall power-conversion efficiency are urgently required. Here, we report the construction of Sb2Se3 solar cells with high-quality Sb2Se3 nanorod arrays absorber along the [001] direction, which is beneficial for sun-light absorption and charge carrier extraction. An efficiency of 9.2%, which is the highest value reported so far for this type of solar cells, is achieved by junction interface engineering. Our cell design provides an approach to further improve the efficiency of Sb2Se3-based solar cells.

a b s t r a c t ⇑ Corresponding authors.

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Solar-heating catalysis has the potential to realize zero artificial energy consumption, which is restricted by the low ambient solar heating temperatures of photothermal materials. Here, we propose the concept of using heterostructures of black photothermal materials (such as Bi2Te3) and infrared insulating materials (Cu) to elevate solar heating temperatures. Consequently, the heterostructure of Bi2Te3 and Cu (Bi2Te3/Cu) increases the 1 sun-heating temperature of Bi2Te3 from 93 °C to 317 °C by achieving the synergy of 89% solar absorption and 5% infrared radiation. This strategy is applicable for various black photothermal materials to raise the 1 sun-heating temperatures of Ti2O3, Cu2Se, and Cu2S to 295 °C, 271 °C, and 248 °C, respectively. The Bi2Te3/Cu-based device is able to heat CuOx/ZnO/Al2O3 nanosheets to 305 °C under 1 sun irradiation, and this system shows a 1 sun-driven hydrogen production rate of 310 mmol g−1 h−1 from methanol and water, at least 6 times greater than that of all solar-driven systems to date, with 30.1% solar-to-hydrogen efficiency and 20-day operating stability. Furthermore, this system is enlarged to 6 m2 to generate 23.27 m3/day of hydrogen under outdoor sunlight irradiation in the spring, revealing its potential for industrial manufacture.

The assembling heterojunction, one of the key topics in photocatalysts and semiconductors (SCs), is generally accomplished in at least two steps, of which the first step is the synthesis of a matrix, and then the growth of the second phase on the matrix. Herein we present the preparation of α/β-Bi2O3 heterojunctions by an in situ phase transformation technique. Under normal pressure, a facile citrate method was used to synthesize β-Bi2O3 nanosheets and α/β-Bi2O3 heterojunctions. The novel features of the process are the mild operating conditions by an appropriate selection of heat treatment temperature and time. Using transmission electron microscopy (TEM), we found that a number of nano-sized α-Bi2O3 form on the β-Bi2O3 nanosheet via a controlled β→α phase transition, generating a large number of heterojunctions. The CM1 (calcining β-Bi2O3 precursor at 363 °C for 4 h) heterojunction achieves a strong visible light absorption and dye absorption capacity and produces a very high reaction rate for Rhodamine B (RhB) photodegradation. Electrochemical impedance spectroscopy (EIS) revealed excellent charge transfer characteristics of the heterojunction, which accounts for its high photoactivity. Using the X-ray electron valence band spectra, it is found that the valence band of α-Bi2O3 is more negative than that of β-Bi2O3. Thus, in heterojunctions, the photogenerated holes in β-Bi2O3 are transferred to α-Bi2O3 with good charge transport characteristics by the intrinsic driving force in the interface field. Furthermore, a separated hole can accomplish a transfer process from α-Bi2O3 to the aqueous solution within its lifetime due to the diameter of α-Bi2O3 being less than 17.6 nm.