Search

Defects present in the absorber layer largely dictate photovoltaic device performance. Recently, a binary photovoltaic material, Sb2Se3, has drawn much attention due to its low-cost and nontoxic constituents and rapid performance promotion. So far, however, the intrinsic defects of Sb2Se3 remain elusive. Here, through a combined theoretical and experimental investigation, we revealed that shallow acceptors, SeSb antisites, are the dominant defects in Sb2Se3 produced in an Se-rich environment, where deep donors, SbSe and VSe, dominate in Sb2Se3 produced in an Se-poor environment. We further constructed a superstrate CdS/Sb2Se3 thin-film solar cell achieving 5.76% efficiency through in situ Se compensation during Sb2Se3 evaporation and through careful optimization of absorber layer thickness. The understanding of intrinsic defects in Sb2Se3 film and the demonstrated success of in situ Se compensation strategy pave the way for further efficiency improvement of this very promising photovoltaic technology. Copyright © 2017 John Wiley & Sons, Ltd.

ZnMgO/PbS colloidal quantum dot (CQD) photovotaics are constructed through incorporating graphene into the lead sulfide (PbS) CQD layer to improve the open circuit voltage and short circuit current of the device, resulting in a 9.0 ± 0.1% improvement. These devices also possess the advantages of ambient processing and high stability. The incorporation of 2D materials into PbS CQD film opens a new avenue for efficiency improvement of CQD photovoltaics.

Sb2Se3 has attracted great research interest very recently as a promising absorber material for thin film photovoltaics due to its suitable bandgap, high absorption coefficient, and non-toxic, low cost, and earth abundant nature. In this work, a significant efficiency improvement to 4.8% of superstrate cadmium sulfide (CdS)/Sb2Se3 solar cells is obtained by the controlled addition of oxygen during thermal evaporation of Sb2Se3 films. Systematic materials and device physics characterization reveal that oxygen addition during Sb2Se3 film evaporation significantly improves the CdS/Sb2Se3 heterojunction quality through effective passivation of interfacial defect states, resulting in a substantial enhancement in device circuit voltage and short circuit current density. The 4.8% device is the highest efficiency thus far reported for Sb2Se3 thin film solar cells. Copyright © 2015 John Wiley & Sons, Ltd.

This paper reports a facile and low-cost routine for the selective synthesis of vanadium oxides by hydrothermal treatment of V2O5 sol. Our experiments found a defined phase evolution sequence [V2O5 V3O7·H2O VO2 (B) VO2 (A) VO2 (M)] that is strongly dependent on the hydrothermal temperature, pressure, and reaction time. A mechanism for the formation of the vanadium oxides based on the oriented attachment (OA) growth model is proposed and discussed.

Lead halide perovskite quantum dots (QDs) possess color-tunable and narrow-band emissions and are very promising for lighting and display applications, but they suffer from lead toxicity and instability. Although lead-free Bi-based and Sn-based perovskite QDs (CsSnX3, Cs2SnX6, and (CH3NH3)3Bi2X9) are reported, they all show low photoluminescence quantum yield (PLQY) and poor stability. Here, the synthesis of Cs3Bi2Br9 perovskite QDs with high PLQY and excellent stability is reported. Via a green and facile process using ethanol as the antisolvent, as-synthesized Cs3Bi2Br9 QDs show a blue emission at 410 nm with a PLQY up to 19.4%. The whole series of Cs3Bi2X9 (X = Cl, Br, and I) QDs by mixing precursors can cover the photoluminescence emission range from 393 to 545 nm. Furthermore, Cs3Bi2Br9 QDs show excellent photostability and moisture stability due to the all-inorganic nature and the surface passivation by BiOBr, which enables the one-pot synthesis of Cs3Bi2Br9 QD/silica composite. A lead-free perovskite white light-emitting diode is fabricated by simply combining the composite of Cs3Bi2Br9 QD/silica with Y3Al5O12 phosphor. As a new member of lead-free perovskite QDs, Cs3Bi2Br9 QDs open up a new route for the fabrication of optoelectronic devices due to their excellent stability and photophysical characteristics.

Sb2Se3, a V2-VI3 compound semiconductor, has attracted extensive research attention in photovoltaics due to its non-toxicity, low cost and earth-abundant constituents. Herein, a combinatorial approach to optimize the performance of TiO2/Sb2Se3 thin film photovoltaics is employed. By simultaneously conducting a series of experiments in parallel rather than one after another, combinatorial strategy increases experimental throughput and reduces personnel costs. Key parameters such as TiO2 thickness, post-annealing temperature and Sb2Se3 thickness are identified as 65 nm, 450 °C and 850 nm through the combinatorial approach. Finally, in combination with (NH4)2S back surface cleaning, TiO2/Sb2Se3 solar cells with 5.6% efficiency and decent stability are obtained, showcasing the power of high-throughput strategy for accelerating the optimization of Sb2Se3 photovoltaics.