Selenium Environment Research Articles

Arsenite Mediates Selenite Resistance and Reduction in Enterobacter sp. Z1, Thereby Enhancing Bacterial Survival in Selenium Environments.

Arsenic (As) is widely present in the environment, and virtually all bacteria possess a conserved ars operon to resist As toxicity. High selenium (Se) concentrations tend to be cytotoxic. Se has an uneven regional distribution and is added to mitigate As contamination in Se-deficient areas. However, the bacterial response to exogenous Se remains poorly understood. Herein, we found that As(III) presence was crucial for Enterobacter sp. Z1 to develop resistance against Se(IV). Se(IV) reduction served as a detoxification mechanism in bacteria, and our results demonstrated an increase in the production of Se nanoparticles (SeNPs) in the presence of As(III). Tandem mass tag proteomics analysis revealed that the induction of As(III) activated the inositol phosphate, butanoyl-CoA/dodecanoyl-CoA, TCA cycle, and tyrosine metabolism pathways, thereby enhancing bacterial metabolism to resist Se(IV). Additionally, arsHRBC, sdr-mdr, purHD, and grxA were activated to participate in the reduction of Se(IV) into SeNPs. Our findings provide innovative perspectives for exploring As-induced Se biotransformation in prokaryotes.

A follow-up study on factors affecting the recovery of patients with hypothyroidism in different selenium environments

BackgroundHypothyroidism is a major manifestation of autoimmune thyroid diseases (AITD). We previously reported that a low selenium (Se) status was linked to an elevated prevalence of thyroid diseases. We hypothesized that Se status may also influence the restoration of thyroid function. Thus, this study aimed to investigate the factors affecting the recovery of thyroid function in patients with (sub-)clinical hypothyroidism, with a specific focus on Se status.MethodsWe conducted a 6-year prospective cohort study comparing two counties with different Se concentrations. Demographic and disease data were collected from 1,190 individuals (549 Se-adequate and 641 Se-deficient) who completed a follow-up study in 2019. In addition, urinary iodine (I) levels, thyroid function, and serum and nail Se levels were measured. Logistic regression was used to investigate the relationship between Se deficiency and recovery of thyroid function.ResultsSex and smoking status was similar between the two counties studied. Thyroid function recovery rate was significantly higher in Se-deficient counties (46.0% vs. 30.6%, P = 0.008). In the multivariate analysis, our results show that female sex (odds ratio [OR] (95% confidence interval [CI]) = 1.875 (1.080–3.257), P = 0.026] and increasing age [OR (95%CI) = 1.028(1.007–1.049), P = 0.009] were associated with the recovery rate. Additionally, our study revealed that while Se status was significant in the univariate analysis, this association appeared to disappear in the multivariate analysis.ConclusionsFemale sex and increasing age have unfavorable effects on the recovery of thyroid function in patients over 30 years of age with (sub-) clinical hypothyroidism.

Study of high selenium interfering with glucose and one-carbon metabolism in hepatocytes in vitro

To investigate the effects of high selenium environment on the expression of selenoproteins and enzymes related to glucose and one-carbon metabolism in normal human hepatocytes. Ten different concentrations of selenomethionine(SeMet, 0, 0.001, 0.005, 0.01, 0.05, 0.1, 0.5, 1, 5 and 10 μmol/L) was added into the normal human hepatocyts and incubated for 48 hours. The expressions of selenoprotein(GPX1 and SELENOP1) and metabolic enzymes(PHGDH, SHMT1, MTHFR and MS) were analyzed by Western blot. When the concentration of SeMet was 0-10 μmol/L, the expression trend of selenoprotein(GPX1 and SELENOP1) is similar, which first increases and then decreases. There is a slight difference between the inflection points of GPX1 and SELENOP1, which are respectively 0.5 μmol/L and 0.1 μmol/L. The expression trend of serine de novo synthesis pathway key enzymes(PHGDH) and folate cycle metabolizing enzymes(SHMT1, MTHFR and MS) is similar to that of selenoproteins, which also increases first and then decreases, but the inflection points are different, which are respectively 0.1 μmol/L(PHGDH and SHMT1) and 0.01 μmol/L(MTHFR and MS). Under the high selenium environment, the glycolytic bypass-serine de novo synthesis pathway is activated to synthesize endogenous serine due to the insufficient intracellular serine supply, causing abnormal glucose metabolism, which is an important extension to the hypothesis of the molecular mechanism of high selenium causing IR.

Insight into the role of selenization time for highly efficient Mn doped Cu2ZnSn(S,Se)4 thin film based solar cells

In this study, manganese (Mn) doped Cu2ZnSn(S,Se)4 (CMZTSSe) absorption layer films were prepared using a sol–gel method followed by a selenization treatment in a selenium environment. In this paper, we discuss the impact of annealing time on the structure, morphology, and properties of CMZTSSe absorption layer films. The crystal quality of the CMZTSSe films increased, and the major Se occupied the position in CMZTSSe with the increase of the annealing time. When the annealing time was 15 min, a smooth and dense film was obtained. The band gap of CMZTSSe was adjusted between 1.19 and 1.09 eV by adjusting the post-annealing time. The influence mechanisms of the annealing time on the performance of a solar cell were investigated by systematically learning the variation in the shunt resistance (RSh) and series resistance (RS) with the microstructure of the CMZTSSe films selenized at different times. The results showed that the power conversion efficiency (PCE) initially increased and then decreased when the annealing time was increased from 10 to 20 min. The VOC, JSC, and FF have similar change regularity with that of the PCE. At an annealing time of 15 min, the CMZTSSe film had the best crystal quality, RS was at minimum, and RSh was at maximum. The CMZTSSe device achieved a maximum PCE of 4.27%, VOC was 382 mV, JSC was 26.35 mA/cm 2, and FF was 42.34%.

Co-precipitation Synthesis with a Variation of the Sulphur Composition of Kesterite Phase Cu2ZnSnS4 (CZSS) without Annealing Process

Commercially available compound CuInGa (S, Se) can be replaced with emerging quaternary compound Cu2ZnSnS4 (Copper Zinc Tin Sulphur or CZSS) for photovoltaic applications due to the high absorption coefficient and optimum bandgap. Unstable sulphur and the co-existence of binary and ternary phases in CZSS are the main obstacles for a single-phase kesterite quaternary compound. To overcome these issues, the researchers are synthesising the CZSS in presence of sulphur and selenium environment. The sulphurization and selenization are the constraints for the synthesis of CZSS and these processes make it costlier. In the present work, the wet-chemical method (i.e., co-precipitation method) was used to synthesise CZSS without vacuum annealing where the sulphur constituent was controlled by changing the stoichiometric ratio. X-ray diffraction (XRD) and Raman analysis confirm that the synthesised CZSS was in polycrystalline and single-phase kesterite nature. The average crystallite sizes for thiourea 16, 18, 20 mmol were found 15 nm, 17 nm and 17 nm, respectively. Surface morphology of the as-prepared film was identified by scanning electron microscope (SEM) and optical bandgap of the film was obtained ~1.33 eV by UV-visible (UV-vis) analysis. The 18 mmol of thiourea with stoichiometric ratio 4:2:2:9 is found the best optimisation for synthesising the CZSS without vacuum annealing by the co-precipitation method. Thus, the thin film of such synthesised CZSS may be employed for the low-cost photovoltaic application.

Quantum coherence modulation in bismuth selenide topological insulator thin film by ion irradiation

The robust surface states of bismuth selenide (Bi2Se3) topological insulator (TI) that could potentially be harnessed for quantum computing and spintronics applications are often eclipsed by defect-induced bulk carriers. With the objective of suppressing the electronic transport in the bulk, we explore the effects of ion irradiation-driven isoelectronic doping in thin films of Bi2Se3 with 600 keV antimony (Sb+) ions at 45° oblique incidence. The distribution of Sb+ ions introduced into the system has been mapped using Rutherford backscattering spectroscopy. The heavy Sb+ ion irradiation has been observed to cause a change from parabolic magnetoresistance to linear magnetoresistance behavior in the irradiated films due to mobility fluctuations. Subsequent annealing in selenium environment has been found to reverse the damage produced by the irradiation, but with significant modifications in the quantum coherence signatures. Weak antilocalization behavior has been observed in the weak magnetic field limit and has been analyzed within the purview of the Hikami-Larkin-Nagaoka model. It has been found that the channel-separated Bi2Se3 film becomes completely channel-mixed due to the induced defects, yielding a system with a single coherent channel upon irradiation. In the as-deposited film, the temperature-dependent power law decay of the coherence length has been found to have two different exponents within the measured temperature range. On the other hand, the irradiated-annealed film has a single decay exponent which has been found to tend to − 0.5, indicating that electron-electron interaction is the only de-phasing mechanism involved. This work establishes the effectiveness of ion irradiation in tuning the quantum coherence phenomena in Bi-based TI systems.

Green and low-cost preparation of CIGSe thin film by a nanocrystals ink based spin-coating method

An “ink” solution based process, using spin-coating technique, followed by annealing in selenium environment with different temperature programs was utilized to prepare CIGSe thin films. Herein, the CuIn0.7Ga0.3Se2 nanocrystals were synthesized using ethanol — a “green” solvent. Three different solvents: 2-propanol, 2-methoxyethanol, and their 2: 1 mixture (v/v ratio), were investigated as a dispersion medium for the as-synthesized CIGSe nanocrystals to form a stable ink solution. The last one- a mixture of 2-propanol: 2-methoxyethanol=2: 1 (v/v), was found to be the most suitable. Furthermore, the influences of various annealing modes on the CIGSe grain size and density in the resulting film were also studied. The as-prepared CIGSe thin film was around 1 µm thick and possessed a tetragonal structure. A newly developed cheaper and “greener” non-vacuum process was applied successfully from the synthesis of nanocrystals to the formation of ink solution, and produced high quality thin films; this opens a new route to the cost-competitive commercialization of CIGSe thin film solar cells.

Quick selenium accumulation in the selenium-rich rice and its physiological responses in changing selenium environments

BackgroundThe element selenium (Se) deficiency is thought to be a global human health problem, which could disperse by daily-supplement from Se-rich food. Increasing the accumulation of Se in rice grain is an approach matched to these nutrient demands. Nonetheless, Se is shown to be essential but also toxic to plants, with a narrow margin between deficiency and toxicity. Notably, the regulatory mechanism balancing the accumulation and tolerance of Se in Se-rich rice plants remains unknown.ResultsIn this study, we investigated the phenotypical, physiological, and biochemical alterations of Se-rich rice in the exposure to a variety of Se applications. Results showed that the Se-rich rice was able to accumulate more abundance of Se from the root under a low Se environment comparing to the Se-free rice. Besides, excessive Se led to phytotoxic effects on Se-rich rice plants by inducing chlorosis and dwarfness, decreasing the contents of antioxidant, and exacerbating oxidative stresses. Furthermore, both phosphate transporter OsPT2 and sulfate transporters OsSultr1;2 may contribute to the uptake of selenate in rice.ConclusionsSe-rich red rice is more sensitive to exogenous application of Se, while and the most effective application of Se in roots of Se-rich rice was reached in 20 μM. Our findings present a direct way to evaluate the toxic effects of Se-rich rice in the Se contaminated field. Conclusively, some long-term field trial strategies are suggested to be included in the evaluation of risks and benefits within various field managements.

Exposure to a high selenium environment in Punjab, India: Effects on blood chemistry.

Many studies have shown that overexposure to environmental selenium may exert a wide pattern of adverse effects on human health, but much uncertainty still surrounds some of them as well as the exact amounts of exposure involved. In particular, very few studies have addressed the possible changes in blood chemistry following high selenium exposure. In a Northeastern part of Punjab, India, very high soil selenium content has been documented, with a value exceeding 2mg/kg (up to 5) as compared with the <0.5mg/kg selenium content characterizing the surrounding referent areas. In seven villages located in that seleniferous areas, we carried out a survey by recruiting volunteers and sampling blood, hair and nail specimens. We administered a questionnaire to the participants and analyzed the specimens for the selenium, along with a series of biochemical and haematological parameters in blood. We included 680 adult volunteers (267 men and 413 women), who showed median selenium levels of 171.30µg/L in serum, 1.25µg/g in hair, and 5.7µg/g in nails. Overall, increasing selenium exposure tended to correlate with higher levels of total cholesterol, albumin, free triiodothyronine, deionidase activity, and with red cell and platelet counts. After stratifying the subjects according to category of selenium exposure, we observed a dose-response relation between serum selenium and risk of high total cholesterol, and between hair selenium and risk of high total and low-density lipoprotein cholesterol, high pancreatic lipase, altered thyroid-stimulating hormone and free triiodothyronine levels. Nail selenium exposure category positively correlated with risk of high alanine-aminotransferase, altered albumin levels, high pancreatic lipase and low levels of thyroid-stimulating hormone. Chronic selenium overexposure appears to adversely affect lipid profiles and pancreatic, liver, and thyroid function, with selenium biomarkers having different abilities to predict such effects.

Exposure to a high selenium environment in Punjab, India: Biomarkers and health conditions

Seleniferous areas have been identified and described in many parts of the world. Despite the interest in selenium as a trace element of considerable toxicologic and nutritional relevance, however, only a few studies have been carried out on human health effects of such high selenium environments. We collected blood, hair and nail samples from 680 adult volunteers (267 men and 413 women) living in seven villages located in the seleniferous area of Punjab, India. We measured selenium levels in these specimens. We also administered a questionnaire to collect information about diet and other lifestyle characteristics, to identify the sources of selenium exposure and to correlate it with a number of health conditions. Serum and hair selenium contents were highly correlated, while the association of these biomarkers with nail selenium content was weaker. Serum selenium showed limited association with consumption of locally produced foods, while pulses and vegetables, along with cereals and pulses, were associated to higher hair and nail selenium contents, respectively. Association of a number of adverse health endpoints with serum and hair selenium was stronger than for nail selenium contents. Such endpoints included higher prevalence of nausea and vomiting, bad breath, worm infestation, breathlessness exert and bad breath, chest pain, hair and nail abnormalities and loss, garlic odor, edema, spontaneous abortion, and overall selenosis. In contrast, we gathered no evidence of dermatitis or loss of appetite in residents most exposed to selenium. Overall, and despite some statistical imprecision in effect estimates, these results confirm the occurrence of adverse health effects in subjects exposed to high levels of environmental selenium. Nail selenium contents may be less adequate to reflect and monitor such overexposure, compared with blood and hair levels.

Interplay Between Relaxation and Resonance in Ultrasound Attenuation by the Cubic Crystal ZnSe:Cr

Resonance ultrasound attenuation, albeit broadened, is observed in doped cubic crystal ZnSe with a part of the Zn2+ ions substituted by magnetic anisotropic Cr2+ ions. In the tetrahedral selenium environment the latter form a T term Jahn–Teller (JT) center with a T⊗e JT problem and three equivalent distortions along the three tetragonal axes. In sufficiently strong magnetic fields (B &gt; 4 T) applied along the [001] direction the degeneracy of the ground state is removed, and the ultrasound wave propagating along [110] and polarized along (at T = 1.3 K) does not interact with the center, its impurity attenuation being reduced to zero. By comparison, this allows to estimate the contribution of the Cr centers to the attenuation of ultrasound in the ZnSe:Cr crystal in zero magnetic field. The experimental data revealed a strong dependence of the attenuation on the ultrasound frequency, evidencing for the resonance nature of the attenuation: there is no frequency dependence in relaxational attenuation with the relaxation time much larger than the period of the ultrasonic wave. The resonance attenuation is attributed to transitions between the ground state energy levels, split by spin‐orbital interaction. The high sensitivity of the resonance absorption on the ultrasound power is also discussed.

Blood pressure levels and hypertension prevalence in a high selenium environment: results from a cross-sectional study

Background and aimsRecent human and laboratory studies have suggested the possibility that selenium overexposure may increase blood pressure. We sought to ascertain whether adults living in a seleniferous area exhibit an association between selenium exposure and both blood pressure levels as well as prevalence of hypertension. Methods and resultsWe measured selenium levels in blood (serum), hair and nail samples obtained from 680 adult volunteers (267 men and 413 women), living in seven Punjabi villages in a seleniferous area and related them to health outcomes, including systolic and diastolic blood pressure and presence of hypertension. In a multivariable restricted cubic spline regression model, adjusted for age, sex and history of hypertension, we found a positive association between systolic blood pressure and both serum (P = 0.004) and hair (P = 0.058) selenium levels, but not with nail selenium content. Little association emerged between the three selenium biomarkers and diastolic blood pressure. Hypertension prevalence was positively associated with the three exposure indicators (P < 0.001). The associations we found were generally stronger in women than in men. ConclusionsOverall, these findings suggest that chronic overexposure to environmental selenium may increase blood pressure, though there were inconsistencies for this association according to the choice of exposure indicator, the study endpoint and the sex.

Post-growth annealing effect on the performance of Cu2SnSe3 solar cells

In this work, the effect of post-deposition annealing in selenium environment was studied on Cu2SnSe3 thin film solar cells prepared from solid solution by doctor blade method. XRD pattern confirms deposited films are of polycrystalline nature having cubic phases with (1 1 1) orientation. The crystallinity improves with the increase in annealing temperature. At high annealing temperature surface agglomeration was found which is due to the melting and re-evaporation of the components from the surface. Electrical properties like carrier mobility, conductivity also modified with the increase in annealing temperature. Maximum efficiency of 1.17% was achieved for the sample annealed at 400 °C having barrier height (ϕb), ideality factor (n) and series resistance (Rs) nearly equal to 0.71 eV, 1.5 and 69 Ω respectively.

Selenization of CIS and CIGS layers deposited by chemical spray pyrolysis

Cu(In1 − xGax)Se2 (CIGS) thin films with x = 0 (CIS) and x = 0.3 (CIGS) were prepared on Mo-coated glass substrate by using chemical spray pyrolysis at a substrate temperature of 350 °C, followed by selenization treatment at 550 °C in selenium environment under N2 gas flow. X-ray diffraction patterns of as-deposited CIGS layers on Mo showed polycrystalline chalcopyrite phase with an intense (112) plane. Splitting of (204)/(220) and (116)/(312) planes for the film with x = 0.3 reveals deviation of tetragonal nature. Field emission scanning electron microscopy cross-sectional images of selenized films showed clear re-crystallization of grains. During the selenization process of the CIGS absorber, a thin interface layer of MoSe2 is formed. Line mapping of Mo/CIGS layer showed more gallium segregation at the interface of back contact resulting in band gap grading. Chemical composition and mapping of the as-deposited and selenized samples were determined by energy dispersive analysis of X-rays. This work leads to fabrication of low cost and large scale Mo/CIGS/CdS/ZnO/ZnO:Al device structure.

Synthesis, characterization and thermal decomposition of tetramethylammonium rare earth double selenates

A series of double selenates, as (CH3)4NLn(SeO4)24H2O (Ln = Rare earth ion like La, Pr, Nd, Sm, Gd, Tb, Dy) was crystallized from mixed solution and characterized in detail for their structure, vibrational and optical properties as well as thermal stabilities. The crystal structure of the praseodymium compound was obtained by single crystal X-ray diffraction (XRD) and revealed a monoclinic (C2/c) lattice with chains formed by PrO8 and SeO4 units. The chains with compositions [Pr(SeO4)4(H2O)4]─ are stacked in three dimensions and the (CH3)4N+ ions located in between them provide charge neutrality to the structure. The characterization of other compounds were carried out from powder XRD data and revealed that they all are isostructural to Pr-compound. All the functional groups were identified by Raman and IR spectroscopic studies. Solid state 77Se NMR revealed noticeable changes in selenium environment in these compounds. The optical absorption studies on the compounds show strong band edge absorptions in UV region. Thermal stabilities of the compounds, as investigated by simultaneous TG-DTA techniques indicate their sequential decompositions due to loss of H2O, (CH3)4N+ group, SeO2 and finally leaving their corresponding rare earth oxides.

Fabrication of pulsed laser deposited Ge doped CZTSSe thin film based solar cells: Influence of selenization treatment

In the present work, Ge doped CZTGeS thin films are pulsed laser deposited followed by annealing treatment in selenium environment. The influence of selenization condition on the structural, morphological, optical and electrical properties of the absorber thin films are investigated. The thin films characterized using X-ray diffraction (XRD) and Raman spectroscopy techniques confirm the formation of Kesterite CZTGeSSe thin film compound with dominant A1 mode vibration. The morphological and optical studies of the thin films reveal the formation of compact and void free microstructure with optimal band gap in the range of 1–1.2eV. The impact of selenization temperature on the quality of thin films has been studied and thin film solar cells are fabricated with CZTGeSSe absorbers grown at various annealing temperatures from 525 to 575℃ to evaluate the performance of devices as a function of an annealing temperature. The elemental Ge and Sn losses from the absorber compound confirmed from X-ray fluorescence spectroscopy (XRF) depended on the annealing temperature and linearly increased with increasing temperature affecting the optical, compositional and microstructural properties of the thin films. Compositional non uniformity is one of the factors that limit the performance of solar cell device. PLD technique due to its advantage of achieving precise stoichiometry control combined with optimized selenization conditions can potentially address the issue. Compared to solar cell fabricated from absorber compound annealed at 525 and 575℃, the solar cell fabricated from the absorber annealed at 550℃ exhibited the best conversion efficiency of 3.82% with Voc 434mV, Jsc 18.33mA/cm2, FF 47.0% and retained nearly 90% power conversion efficiency (PCE) stability after time period of 60 days.

Properties of Electron-Beam Irradiated CuInSe2 Layers by Multi-Step Sputtering Method.

Typically, CuInSe2 (CIS) based thin films for photovoltaic devices are deposited by co-evaporation or by deposition of the metals, followed by treatment in a selenium environment. This article describes CIS films that are instead deposited by DC and RF magnetron sputtering from binary Cu2Se and In2Se3 targets without the supply of selenium. As a novel method, electron beam annealing was used for crystallization of Cu2Se/In2Se3 stacked precursors. The surface, cross-sectional morphology, and compositional ratio of CIS films were investigated to confirm the possibility in crystallization without any addition of selenium. Our work demonstrates that the e-beam annealing method can be a good candidate for the rapid crystallization of Cu-In-Se sputtered precursors.

Structure of Arsenic Selenide Glasses Studied by NMR: Selenium Chain Length Distributions and the Flory Model

Five homogeneous arsenic selenide glasses with target compositions As2Se3, AsSe2, AsSe3, AsSe4.5, and AsSe6 were studied quantitatively by 77Se Carr–Purcell–Meiboom–Gill magic-angle spinning NMR and transmission electron microscopy–energy-dispersive X-ray spectroscopy. The entire set of NMR spectra is simultaneously fitted with six distinct environments taking into account the effect of first and second neighbors on the position of the 77Se resonance. The selenium chains are bound at each end to trivalent arsenic atoms, and the chain length distribution can be modeled with the Flory theory, which is well-known in polymer science and is used here for the first time to model the probability of finding each selenium environment in a selenide glass. No arsenic homopolar bond is detected in our experiments.

Cu2ZnSnSe4 nanocrystals capped with S(2-) by ligand exchange: utilizing energy level alignment for efficiently reducing carrier rec ombination.

In this work, we employed a convenient one-step synthesis method for synthesizing Cu2ZnSnSe4 (CZTSe) nanocrystals (NCs) in an excess selenium environment. This excess selenium situation enhanced the reaction of metal acetylacetonates with selenium, resulting in the burst nucleation of NCs at relatively low temperatures. The phase morphology and surface and optoelectronic properties of NCs before and after ligand exchange were discussed in depth. It was found that pure tetragonal-phase structure CZTSe NCs with approximately 1.7-eV bandgap could be synthesized. The removal of large organic molecules on CZTSe NCs after ligand exchange by S2− decreased the resistivity. The bandgap of the films after ligand exchange by 550°C selenization was also decreased due to better crystallinity. For potential application in CZTSe solar cells, we constructed an energy level diagram to explain the mutual effect between the absorption layer and CdS layer. Using cyclic voltammetry (CV) measurement, we found that the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of CZTSe films shifted down after ligand exchange. After energy level alignment at the CdS/CZTSe interface, a type I band alignment structure was more conveniently formed after ligand exchange. This structure acted as the barrier against injection electrons from ZnO to the CZTSe layer, and recombination would subsequently be depressed.

Influence of the Se environment on Cu-rich CIS devices

Besides their better electronic properties, Cu-rich CuInSe2 solar cells performed worse than the Cu-poor ones. Dominated by interface recombination which lowers their open circuit voltage, they also exhibit lower current. They are indeed limited by a high native doping which leads to tunneling enhanced recombination. In order to decrease this doping, we investigate the effect of the selenium environment during the absorber growth. We demonstrate that the chemical activity of the Se during the growth strongly influences both the film microstructure and the solar cell performance via various structural and opto-electronic characterization on both the absorber and the resulting solar cells: scanning electron microscopy, energy dispersive X-ray spectrometry, X-ray diffraction in addition to classical current–voltage and quantum efficiency measurements on the solar cell devices. We show that low Se environment is beneficial to obtain better Cu-rich solar cells.