SnO2 Sn Research Articles

Efficient and stable perovskite solar cells via oxalic acid doped SnO2 nanocrystals with surface-defect passivation

The electron extraction and transfer play a crucial role in high performance of perovskite solar cells (PSCs). Tin dioxide (SnO2), with the high electrical conductivity and low photocatalytic activity, has been reported to be one of the most advantageous electron-transporting layers (ETL) in PSCs. However, a large number of non-radiative recombination defects have been reported in SnO2, which are attributed to the low tunability and lower dispersibility. Here, we propose a ligand-assisted tuning strategy based on the oxalic acid (OA) modification to control the SnO2 film and interfacial structure. This strategy can effectively inhibit the particle aggregation of SnO2 film. In addition, the bonding interaction between CO in the ligand and Sn in SnO2 and Pb atoms in the perovskite reduces the interfacial contact impedance and enhances the electron extraction. As a result, an impressive PCE of 22.68 %, a fill factor exceeding 0.82 and a Voc of 1.15 V were successfully obtained. In addition, the unencapsulated PSCs can maintain an initial efficiency of 93 % upon exposure to ambient air for 500 h.

Tetramethylammonium hexafluorophosphate interface modification for high-efficiency perovskite solar cells

Interface modification has been proved to be an effective method to improve the performance of perovskite solar cells (PSCs). In this paper, tetramethylammonium hexafluorophosphate (TMAPF6) is employed to modify the interface of SnO2/perovskite. Fluorine (F) in PF6 − will fill the oxygen vacancy by interacting with Sn in SnO2. Meanwhile, TMA+ and PF6 − in TMAPF6 will effectively fill the MA+ and I− vacancy in the interface. TMAPF6 modification enhances the hydrophobicity of the SnO2 surface, promotes the growth of high-quality perovskite film with large grain size, and then significantly suppresses the non-radiative recombination of PSCs. Furthermore, the TMAPF6 modification introduces a better energy level alignment between SnO2 and perovskite layer, enabling a more efficient electron extraction. As a result, the TMAPF6-modified MAPbI3 PSC achieves a significantly increasing power conversion efficiency (PCE) from 18.62% to 20.92% and an improved stability with only 15% PCE drop after 600 h of storage in air. This work develops an efficient interface modification molecule to increase the efficiency of PSCs, which would be a promising strategy for the large-scale commercialization of the photovoltaic devices.

Improved Efficiency of Perovskite Solar Cells Using a Nitrogen-Doped Graphene-Oxide-Treated Tin Oxide Layer.

Tin oxide (SnO2) is widely adopted as an electron transport layer in perovskite solar cells (PeSCs) because it has high electron mobility, excellent charge selective behavior owing to a large band gap of 3.76 eV, and low-temperature processibility. To achieve highly efficient SnO2-based PeSCs, it is necessary to control the oxygen vacancies in the SnO2 layer, since the electrical and optical properties vary depending on the oxidation state of Sn. This study demonstrates that the performance of PeSCs may be improved by using nitrogen-doped graphene oxide (NGO) as an oxidizing agent for SnO2. Since NGO changes the oxidation state of the Sn in SnO2 from Sn2+ to Sn4+, the oxygen vacancies in SnO2 can be reduced using NGO. Multiple devices are fabricated, and various techniques are used to assess their performance, including X-ray photoelectron spectroscopy, dark current analysis, and the dependence of the open-circuit voltage on light intensity. Compared with the average power conversion efficiency (PCE) of control devices, PeSCs with SnO2:NGO composite layers exhibit greater PCEs with less deviation. Therefore, the introduction of NGO in a SnO2 layer can be regarded as an effective method of controlling the oxidation state of SnO2 to improve the performance of PeSCs.

Effect of (Ni-Ag) co-doping on crystal structure and magnetic Property of SnO2

In this work, a series of (Ni-Ag) co-doped SnO2 compounds i.e. Sn1-x-yNix AgyO2 (x = 0–0.12 and y = 0–0.12) compounds have been prepared by the solid-state reaction route. The x-ray diffraction patterns (XRD) indicate that these compounds crystallize to rutile phase with tetragonal structure. Temperature variation of magnetization (M-T) of these compounds indicates that the co-doping of Ni and Ag in place of Sn in SnO2 gives rise the increase in magnetization. One of the striking features observed from the M-T measurement is the relatively large Curie temperature (θC) in the order of 721.2 K and 675.7 K for Sn0.94Ag0.06O2 and Sn0.94Ni0.06O2 compounds. The θC is found to decrease systematically upon Ni-Ag co-doping. The M-H curves at the room temperature indicate that the saturation magnetization, area under the hysteresis loop and the coercive field increases with the increase in (Ni-Ag) co-doping upto x = y = 0.06 (i.e. 6%). However, for further co-doping, these parameters were found to decrease.

Studies of dense electronic excitation-induced modification in crystalline Fe-doped SnO2 thin films

Dense electronic excitation-induced modification in thin films of Fe-doped tin oxide (SnO2) grown by RF sputtering technique was done by irradiating swift heavy ion (SHI) beams of 100MeV Au8+ with varying ion fluencies from 5×1011 to 1×1013 ions/cm2. While the AFM results exhibit grain size dependence on irradiation fluence, MFM images show uniformly distributed magnetized nanoparticles over the entire surface after irradiation. GAXRD pattern indicates particle size variation (from 5 to 26nm) due to irradiation and higher stability of (101) other planes against irradiation. Our reported results show that the surface energies of ESurf(101)>ESurf(110) in rutile structure of SnO2. Change in optical band gap between 3.78 and 5.08eV due to variation fluence was observed. This is attributed to variation in particle size, scattering due to surface roughness and modification in local electronic structure. RT magnetic studies done by SQUID shows that coercivity increases up to the fluence of 5×1012ions/cm2 (157.71Oe). The increase in coercivity is due to oxygen vacancies created and change in local electronic structure of Sn due to recoil implantation. Resonance RBS results confirm the presence of Fe in the samples with a new observation where increase in peak intensity of Sn after irradiation occurred. The presence of X-ray absorption near-edge structure spectra at O K-edge around 532.63eV in pristine and irradiated samples confirms the doping of Fe at the lattice site of Sn in SnO2. Evolution of new spectral features at 486.09, 486.75, 491.40, 492.85 and 499.14eV for XANES at Sn M-edge was obtained after irradiation.

First-principles study of optical and electronic properties of N-doped SnO2

Using first-principles full potential linearized augmented plane wave method (FP-LAPW), we present the isosurface of spin density, total density of states and optical properties of undoped SnO2, substitutional N for O and substitutional N for Sn in SnO2. The results show that the band gap in two kinds of N-doped SnO2 is wider than that of SnO2 eigenstate, and the imaginary part of the dielectric function makes a blue shift corresponding to the increasing band gaps. It points out the relationship between electronic structure and optical properties in theory.

X-Ray Study of the Band Structure in Stannic Oxide

In this article we present the experimental data on L3-absorption spectra of metallic tin. and tin in SnO2 . We have used (i) a bent crystal spectrometer and (ii) a high resolution flat crystal spectrometer with a microfocus target as the source for the continuum radiation. We have observed a “white line” on the low energy side of the primary L3-absorption edge of Sn in SnO2. Similar “white lines” in absorption spectra were reported earlier by M. Siegbahn in rare earth elements with f-vancies, who designated such lines appearing immedlately on the low energy side of the primary absorption edge as “white lines” in absorption spectra. It is interesting to note that metallic tin does not reveal the “white line”, while Sn in SnO2 clearly revealed a sharp white line on the low energy side of the primary absorption edge.