Surface-Modified Graphene Oxide/Lead Sulfide Hybrid Film-Forming Ink for High-Efficiency Bulk Nano-Heterojunction Colloidal Quantum Dot Solar Cells

Abstract

Solution-processed colloidal quantum dot solar cells (CQDSCs) is a promising candidate for new generation solar cells. To obtain stable and high performance lead sulfide (PbS)-based CQDSCs, high carrier mobility and low non-radiative recombination center density in the PbS CQDs active layer are required. In order to effectively improve the carrier mobility in PbS CQDs layer of CQDSCs, butylamine (BTA)-modified graphene oxide (BTA@GO) is first utilized in PbS-PbX2 (X = I−, Br−) CQDs ink to deposit the active layer of CQDSCs through one-step spin-coating method. Such surface treatment of GO dramatically upholds the intrinsic superior hole transfer peculiarity of GO and attenuates the hydrophilicity of GO in order to allow for its good dispersibility in ink solvent. The introduction of BTA@GO in CQDs layer can build up a bulk nano-heterojunction architecture, which provides a smooth charge carrier transport channel in turn improves the carrier mobility and conductivity, extends the carriers lifetime and reduces the trap density of PbS-PbX2 CQDs film. Finally, the BTA@GO/PbS-PbX2 hybrid CQDs film-based relatively large-area (0.35 cm2) CQDSCs shows a champion power conversion efficiency of 11.7% which is increased by 23.1% compared with the control device.

In-Depth Exploration of the Charge Dynamics in Surface-Passivated ZnO Nanowires

“…The ground-state absorption spectra and TA spectra (ranging from 850 to 1050 nm) of PbS QD film, ZnO NW/PbS QD film, and ZnO@SnO 2 NW/PbS QD film are shown in Figure S2. The ground-state absorption and TA bleaching peaks of these three films are all around 960 nm, which correspond to the lowest energy excitons in PbS QDs . The TA bleaching decay curves (probe wavelength of 960 nm) for PbS QD film, ZnO NW/PbS QD film, and ZnO@SnO 2 NW/PbS QD film are shown in Figure b.…”

“…The ground-state absorption and TA bleaching peaks of these three films are all around 960 nm, which correspond to the lowest energy excitons in PbS QDs. 32 The TA bleaching decay curves (probe wavelength of 960 nm) for PbS QD film, ZnO NW/PbS QD film, and ZnO@SnO 2 NW/ PbS QD film are shown in Figure 3b. It is known that the TA bleaching decay shows a much longer time constant more than 1 ns for colloidal PbS QDs in solution, 26 thus the faster TA bleaching decay here can be considered to mostly reflect the charge transfer (including the charge separation in the PbS QD films) occurring in these films.…”

Optimizing the Synthetic Conditions of “Green” Colloidal AgBiS2 Nanocrystals Using a Low-Cost Sulfur Source

“…Colloidal AgBiS 2 nanocrystal (NC), a member of the I–V–VI 2 ternary semiconductor materials [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ], is a promising eco–friendly material for solar cells owing to colloidal AgBiS 2 NC having a wide absorption spectrum in the visible to near–infrared region (300–1600 nm) [ 8 , 9 , 10 ], high absorption coefficient (~10 5 cm −1 ) [ 1 , 11 , 12 , 13 ], and good air stability [ 8 ]. The hot injection method is widely used to prepare high quality NCs such as PbS [ 14 ], PbSe [ 15 , 16 ], and halide perovskite NCs [ 17 , 18 , 19 , 20 , 21 , 22 ]. In 2016, Bernechea et al synthesized colloidal AgBiS 2 NCs by the hot injection method using hexamethyldisilathiane (TMS) as the sulfur source and first reported colloidal AgBiS 2 NC–based solar cells with a certified power conversion efficiency (PCE) of 6.3% [ 1 ].…”

Coumarin-Modified CQDs for Biomedical Applications—Two-Step Synthesis and Characterization

“…Until now, CQDs were obtained from many different carbon-rich materials, including waste biomass such as fruit peels, vegetables, coffee grounds or even milk [24]. Thus, they are gradually replacing semiconductor-based nanomaterials in both biomedical, electrooptical and environmental applications including solar cells development [26], in vivo bioimaging [25], metal ions [27] or even microorganisms' detection [28].…”