Antimony chalcogenides (Sb
2
X
3
, X = S and Se) are intriguing materials for the fabrication of next-generation, flexible/wearable, lightweight, and tandem photovoltaic (PV) devices. Recently, the ...power conversion efficiency (PCE) of 10.75% and 11.66% has been demonstrated in (single junction) Sb
2
X
3
and Sb
2
X
3
/Si (tandem) solar cells, respectively. However, the inevitable presence (>10
16
cm
−3
) of deep-level defects (especially Sb
S
and Sb
Se
antisites) induces Fermi-level (
E
F
) pinning, accelerates Shockley-Read-Hall (SRH) recombination, and shortens the carrier lifetime. Unambiguously, these defects result in sluggish charge transport and high open-circuit voltage (
V
OC
) deficits in the corresponding Sb
2
X
3
solar cells. Therefore, a comprehensive understanding of the deep-level defects and their passivation strategies can be instrumental in reducing the
V
OC
deficits and boosting the PCE values. In this regard, the present review highlights the expanding toolbox of defect-engineering strategies for Sb
2
X
3
films, laying a solid foundation for improving the PCE of Sb
2
X
3
solar cells.
Antimony chalcogenides (Sb
2
X
3
, X = S and Se) are intriguing materials for flexible/wearable, lightweight, and tandem photovoltaic devices. This work highlights the deep-level defect engineering strategies for Sb
2
X
3
thin-film solar cells.
•(GeSe4)100-x(As2Se3)x glasses with x in the range 0 ≤ x ≤ 100 are prepared by melt quenching.•Glass forming ability and thermal stability of all these glasses are found to be high.•These glasses ...exhibit minimum fragility indicating their melts are strong.•Melts of glasses in the range 0 ≤ x ≤ 30 are super strong in nature.•They transmit IR light over a wide wavelength range.
(GeSe4)100-x (As2Se3)x glasses in the GeSe4-As2Se3 pseudo-binary joint are prepared by the melt quenching method. In this tie-line, the entire composition 0 ≤ x ≤ 100 is characterized by fixed average network connectivity of 2.40, which is considered to be optimal connectivity as the number of constraints and the number degrees of freedom available to the atoms are balanced at this average connectivity. The glass forming ability of the glasses having this average connectivity of 2.40 is usually found to be maximum. Glass transition temperature (Tg) decreases till x = 30 and remains invariant in the range 40 ≤ x ≤ 70. For x > 70, Tg shows an increasing trend. The jump in specific heat capacity (ΔCp), non-reversing heat flow (ΔHnr), Tg and the optical bandgap (Eg) show a distinct change in the composition range 40 and 70 mol.% of As2Se3. The fragility index (m) lies in the range of 15 and 32 for all the prepared glasses, representing the strong nature of these glass forming melts in the (GeSe4)100-x (As2Se3)x glasses. The viscosity as a function of reduced temperature (Tg/T) shows almost an Arrhenius nature for 0 ≤ x ≤ 70 and for x > 70, a slight deviation from the Arrhenius behviour is observed. The structural network of these glasses primarily consists of GeSe4/2 and Se-Se chains for x ≤ 30. For 40 ≤ x ≤ 70, the network is dominated by AsSe3/2 pyramidal units and As-As homopolar bonds. For x > 70, the structural network is characterized by AsSe3/2 pyramidal units. All the prepared glasses are found to transmit infrared (IR) light over a wide wavelength range from 2 to 17 μm. The super strong nature of the melts indicates that optical devices can be easily made for IR applications.
In the present study, tellurium-rich (45–55 mol%) As-Se-Te chalcogenide glasses were synthesized and purified further to eliminate the impurities for achieving extended far infrared transmission. The ...glasses were characterized and studied for physical, thermal, optical, structural and mechanical properties. All the glasses have shown transparency in the wavelength range of ∼1.6–19 µm, with >45 % transmission with impurities. The purification process through vacuum distillation has eliminated the oxide impurities in the glass and the glass displayed ∼52 %T in the wide infrared region. The refractive index for purified glass decreased from 3.487 at 2 µm to 3.362 at 10 µm. The purified glass was heat treated for four hours, and the most dominant crystal phase, As2Te3 was observed in XRD analysis. Presence of sharp Raman peak at ∼120 cm−1 belonging to As2Te3 pyramids in heat-treated sample well agreed with the XRD results.
Present investigation explores the structural changes that occur in glass network as a function of compositional variation through Raman spectra of As-Sb-S-I chalcogenide glasses and correlated with ...their bulk mechanical properties. In this study, a series of six glasses are prepared by melt quenching technique. The glass without iodine (G1) is assigned as base glass. The rest of the glass compositions are designed with iodine content either at 10 or 20 mol% and simultaneously varying the As/Sb mol% ratio. The effects of iodine variation in the glass matrix are clearly evident from their Raman spectra as well as bulk mechanical properties which are further validated by theoretical estimated average coordination number . Raman spectra analysis indicates that the peak around 150 cm−1 corresponding to Sb–S bonds increases in amplitude and appearance of peak around 233 cm−1 of As–S bonds in antimony and arsenic rich glasses, respectively. In addition, an intense peak around 490–495 cm−1 and weak peak around 233 cm−1 which are attributed to stretching vibrations S–S and As–S bonds respectively in As2S3 units can be seen only in arsenic rich glasses. The elastic modulus values denote the dependence on antimony content while Vickers hardness values are decreasing with an increase in iodine content. The Raman spectra of raw materials used in glass preparation are also analysed to compare the bonds present in crystalline raw materials to that of amorphous structure in the prepared glasses.
•As-S-Sb-I chalcogenide glass system studied for structural and mechanical properties.•Antimony along with iodine (SbI bonds) loosened the glass network.•SbI bonds decreased the elastic moduli and Vickers hardness of glasses.•Iodine mass effect played a crucial role in density and molar volume trend.•Measured bulk mechanical properties strengthened the claim of Raman analysis.
Present article describes the preparation of new series of chalcogenide glasses in As-Sb-S-I system with an aim to explore its thermal and optical properties. Arsenic and antimony concentrations were ...varied by keeping the concentration of sulphur and iodine constant in the studied glass compositions. Bulk glasses were prepared by following melt quenching technique and then investigated further for thermal stability, optical transmission and impurities present within the resulted glasses. Optical band gap (Eg) was calculated using Tauc equations where it was found that Eg is in harmony with structural arrangement of glasses. The glasses with the combination of higher arsenic and iodine have their UV band edge blue shifted while the glasses with the combination of higher antimony and iodine showing their IR cut-off red shifted.
•AsSbSI chalcogenide glass system explored for its thermal and optical properties.•Glasses shown good thermal stability that is ΔT=108–109°C•Iodine along with arsenic (AsI bonds) helped in blue shift of band edge.•SbI bonds shifted IR band-edge beyond 13μm, impossible with only sulphur glasses.•Iodine has played an important role in enhancing optical window.
