Colloidal-quantum-dot photovoltaics using atomic-ligand passivation

Abstract

Colloidal-quantum-dot (CQD) optoelectronics offer a compelling combination of solution processing and spectral tunability through quantum size effects. So far, CQD solar cells have relied on the use of organic ligands to passivate the surface of the semiconductor nanoparticles. Although inorganic metal chalcogenide ligands have led to record electronic transport parameters in CQD films, no photovoltaic device has been reported based on such compounds. Here we establish an atomic ligand strategy that makes use of monovalent halide anions to enhance electronic transport and successfully passivate surface defects in PbS CQD films. Both time-resolved infrared spectroscopy and transient device characterization indicate that the scheme leads to a shallower trap state distribution than the best organic ligands. Solar cells fabricated following this strategy show up to 6% solar AM1.5G power-conversion efficiency. The CQD films are deposited at room temperature and under ambient atmosphere, rendering the process amenable to low-cost, roll-by-roll fabrication.

Ionic-passivated FeS2 photocapacitors for energy conversion and storage

“…The halide ligand-passivated devices, with longer carrier lifetimes and higher photocurrent, can be attributed to the passivation of FeS 2 surface defect states and fast carrier transport. A similar halide compound passivation effect has also been reported by Sargent et al, 14 where the Br-capped PbS devices showed one order of magnitude faster mobility than that of MPA-and EDT-treated films.…”

“…3 Halide ions have strong affinity for the Fe-terminated cations of FeS 2 (100) surfaces and act as ligands offering a direct approach to highly effective passivation. 14 While this was beneficial, having an aqueous electrolyte solution is detrimental to pyrite due to its known photo-degradation in water. 15 Therefore, utilizing an anhydrous source of I À , from ionic liquids (IL) in this study, could provide the pyrite passivation and still allow charge transfer with minimal degradation.…”

Efficient Water Splitting Cascade Photoanodes with Ligand‐Engineered MnO Cocatalysts

“…In the sulfite oxidation with extremely fast oxidation kinetics, in other words, Na 2 SO 3 removing the injection barrier without affection the charge separation, surface recombination can be negligible. Therefore, most of the previously reported results related to BiVO 4 ‐based photoanodes13, 14, 16, 19, 47, 51, 52, 53 were measured in sulfite oxidation condition to show photo‐electrochemical properties of BiVO 4 ‐based electrodes independently of its poor water oxidation kinetics, as shown in Table S2 (Supporting Information). The photo‐electrochemical current densities of the BiVO 4 ‐based photoanodes4, 13, 14, 16, 17, 19, 20, 21, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 64, 65, 66, 67, 68, 69, 77 were plotted as a function of potential versus RHE.…”

“…The shifts of the band edge energies of MnO can still be tuned over a wide range by controlling the intrinsic dipole moment of the ligand. Since the orientation and coverage of the ligands on the surface, and the contribution of the effective dipole moment are weakly coupled, we can predict the change in the energy shift from the controlled change in the intrinsic dipole moment of the ligand 50, 51, 52, 53, 54…”

An Enhanced UV–Vis–NIR an d Flexible Photodetector Based on Electrospun ZnO Nanowire Array/PbS Quantum Dots Film Heterostructure

“…However, the spatial separation induced by the long oleic acid (OA) ligand that was used to cap QDs34 probably degrade the charge transfer between QDs and NWs. Therefore, it is necessary to exchange the long ligand with short one, such as EDT, tetrabutyl ammonium iodide (TBAI) 35, 36, 37, 38. Herein, 1–2 mL EDT solution was dropped on the device to replace the long ligand of OA for about 2–3 min, see the schematic illustration in Figure 1c.…”