Self-Generated Buried Submicrocavities for High-Performance Near-Infrared Perovskite Light-Emitting Diode.

Embedding submicrocavities is an effective approach to improve the light out-coupling efficiency (LOCE) for planar perovskite light-emitting diodes (PeLEDs). In this work, we employ phenethylammonium iodide (PEAI) to trigger the Ostwald ripening for the downward recrystallization of perovskite, resulting in spontaneous formation of buried submicrocavities as light output coupler. The simulation suggests the buried submicrocavities can improve the LOCE from 26.8 to 36.2% for near-infrared light. Therefore, PeLED yields peak external quantum efficiency (EQE) increasing from 17.3% at current density of 114 mA cm-2 to 25.5% at current density of 109 mA cm-2 and a radiance increasing from 109 to 487 W sr-1 m-2 with low rolling-off. The turn-on voltage decreased from 1.25 to 1.15 V at 0.1 W sr-1 m-2. Besides, downward recrystallization process slightly reduces the trap density from 8.90 × 1015 to 7.27 × 1015 cm-3. This work provides a self-assembly method to integrate buried output coupler for boosting the performance of PeLEDs.

A Bifunctional Carbazide Additive For Durable CsSnI3 Perovskite Solar Cells.

Inorganic CsSnI3 with low toxicity and a narrow bandgap is a promising photovoltaic material. However, the performance of CsSnI3 perovskite solar cells (PSCs) is much lower than that of Pb-based and hybrid Sn-based (e.g., CsPbX3 and CH(NH2 )2 SnX3 ) PSCs, which may be attributed to its poor film-forming property and the deep traps induced by Sn4+ . Here, a bifunctional additive carbazide (CBZ) is adapted to deposit a pinhole-free film and remove the deep traps via two-step annealing. The lone electrons of the NH2 and CO units in CBZ can coordinate with Sn2+ to form a dense film with large grains during the phase transition at 80 °C. The decomposition of CBZ can reduce Sn4+ to Sn2+ during annealing at 150 °C to remove the deep traps. Compared with the control device (4.12%), the maximum efficiency of the CsSnI3 :CBZ PSC reaches 11.21%, which is the highest efficiency of CsSnI3 PSC reported to date. A certified efficiency of 10.90% is obtained by an independent photovoltaic testing laboratory. In addition, the unsealed CsSnI3 :CBZ devices maintain initial efficiencies of ≈100%, 90%, and 80% under an inert atmosphere (60 days), standard maximum power point tracking (650 h at 65 °C), and ambient air (100 h), respectively.

Reciprocally Photovoltaic Light-Emitting Diode Based on Dispersive Perovskite Nanocrystal.

Integrating highly efficient photovoltaic (PV) function into light-emitting diodes (LEDs) for multifunctional display is of great significance for compact low-power electronics, but it remains challenging. Herein, it is demonstrated that solution engineered perovskite nanocrystals (PNCs, ≈100 nm) enable efficient electroluminescence (EL) and PV performance within a single device through tailoring the dispersity and interface. It delivers the maximum brightness of 490 W sr-1  m-2 at 2.7 V and 23.2% EL external quantum efficiency, a record value for near-infrared perovskite LED, as well as 15.23% PV efficiency, among the highest value for nanocrystal perovskite solar cells. The PV-EL performance is well in line with the reciprocity relation. These all-solution-processed PV-LED devices open up viable routes to a variety of advanced applications, from touchless interactive screens to energy harvesting displays and data communication.

Magnetically-mediated regeneration and reuse of core-shell Fe0@FeIII granules for in-situ hydrogen sulfide control in the river sediments.

A novel iron-cycling process based on core-shell iron granules, which contained zero-valent iron (Fe0) in the core and maghemite (γ-Fe2O3) on the shell (Fe0@FeIII granules), was proposed to in-situ control hydrogen sulfide in the sediments of the polluted urban rivers. The Fe0@FeIII granules added in the top sediment layer removed 97% of sulfide generated by sulfate-reducing bacteria in the sediments, and the sulfide removal capacity of virgin granules was 163 mg S/g Fe (114 mg S/g granule). The Fe0@FeIII granules removed the formed sulfide through the abiotic sulfide oxidation and precipitation, and they also stimulated the microbial iron reduction, which competitively consumed wastewater-derived organics and partially inhibited the sulfate reduction in the sediments. The used Fe0@FeIII granules were easily regenerated through magnetic separation from sediments and air exposure for 12 h, which enhanced the sulfide removal capacities of the regenerated granules by 12%-22%, compared to the virgin granules. During the air exposure, ferrous products (i.e., iron sulfide and surface-associated FeII) on the granule shell were completely oxidized to poorly ordered FeIII hydroxides (γ-FeOOH and amorphous FeOOH) having larger specific surface areas and higher reactivity to sulfide than γ-Fe2O3 on the virgin granules. Meanwhile, the Fe0 in the core was also partially oxidized through the indirect electron transfer, which was facilitated by the electrically conductive iron oxide minerals (Fe3O4 and Fe2O3) and the microbial electron carriers (e.g., Geobacter). The oxidation of Fe0 core contributed additional FeIII hydroxides to the sulfide control. The Fe0@FeIII granules were reused for four times in a 293-day trial, and their overall sulfide removal capacity was at least 920 mg S/g Fe. The proposed iron-cycling process can be a chemical-saving, energy-saving and cost-effective approach for the hydrogen sulfide control in the sediments of polluted urban rivers, as well as lakes, aquaculture ponds and marine.