Origin of photovoltaic losses in selenium solar cells with open-circuit voltages approaching 1 V

Nielsen, Rasmus; Youngman, Tomas Hugh; Moustafa, Hadeel; Levcenco, Sergiu; Hempel, Hannes; Crovetto, Andrea; Olsen, Thomas; Hansen, Ole; Chorkendorff, Ib; Unold, Thomas; Vesborg, Peter Christian Kjærgaard

doi:10.1039/d2ta07729a

Cited by 17 publications

(19 citation statements)

References 52 publications

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“…Specifically, the devices using fluorine doped tin oxide (FTO) instead of ITO show no S-shaped kink in the J-V curve, which indicates that the carrier transport barrier could be attributed to the ZnMgO/TCO-interface. ZnMgO was first suggested for use in selenium thin-film solar cells by Todorov et al, 27 and later played a key role in achieving the record opencircuit voltage of V oc =0.99 V. 23 However, all ZnMgO-based selenium solar cells reported in literature have been synthesized on FTO-coated glass, whereas the devices fabricated on ITO use TiO 2 instead of ZnMgO as the n-type contact material. 26,33 To investigate the sensitivity towards the choice of TCO, we synthesize ZnMgO, TiO 2 and poly-Se thin-films and examine their relative energy band positions.…”

Section: Resultsmentioning

confidence: 99%

“…This point is consistent with our previous publications on improving the optoelectronic quality of the selenium absorber. 20,23 However, prior to undertaking elaborate efforts in defect-engineering of selenium, it is essential to determine the appropriate substrate materials on which to grow the absorber. The results of this work demonstrate the significant impact of using ITO instead of FTO.…”

Section: Resultsmentioning

confidence: 99%

“…[15][16][17][18][19][20] This inorganic semiconductor has a reported direct bandgap between 1.8 and 2.0 eV in its trigonal phase, which may be tuned within the range of 1.2-1.8 eV through alloying with tellurium. 21,22 Furthermore, selenium features a very high absorption coefficient (>10 5 cm -1 ) in the visible region, 23 long-term air-stability, 24,25 and its single-element composition and low melting point of 220 • C makes processing simple, potentially low cost, and compatible with most bottom cells. Nevertheless, the research progress on selenium plateaued with an efficiency record of PCE=5.0% achieved by Nakada et.…”

Section: Introductionmentioning

confidence: 99%

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Selenium Thin-Film Solar Cells with Cadmium Sulfide as a Heterojunction Partner

Nielsen

Youngman

Crovetto

et al. 2021

ACS Appl. Energy Mater.

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Elemental selenium (Se) is experiencing a renaissance as a p-type direct wide bandgap (1.95 eV) photoabsorber, appropriate for integration with lower bandgap materials in tandem photovoltaic devices. However, single-junction selenium devices are typically in the superstrate configuration with the charge-separating p–n junction located very close to the substrate. For tandem devices, the p–n junction should ideally lie near the surface of the cell to maximize photocarrier collection, implying that the n-type heterojunction partner should be deposited on top of Se. Since Se is a soft, low-melting-point material, a low-damage deposition technique should then be identified for the partner material. Here, we investigate the suitability of CdS grown by chemical bath deposition as an n-type partner for Se cells. We demonstrate the first functioning CdS/Se solar cell in the standard superstrate configuration. Although it may be possible to realize a substrate configuration, we find that the bandgap and electron affinity of CdS are not optimal for efficient carrier absorption and transport in selenium devices, suggesting that CdS is a poor partner for selenium.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Selenium Thin-Film Solar Cells with Cadmium Sulfide as a Heterojunction Partner

Nielsen

Youngman

Crovetto

et al. 2021

ACS Appl. Energy Mater.

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“…Laser-annealing is a compelling alternative to thermal annealing, as the energy induced upon exposure may be accurately localized in time and space. , This enables excellent control of the crystallization process as well as the crystal growth direction. The latter is particularly important in the case of trigonal selenium, as the optoelectronic material properties are anisotropic . The crystallographic orientation of the grains in the selenium thin-film is therefore expected to affect the PV device performance.…”

Section: Introductionmentioning

confidence: 99%

“…The latter is particularly important in the case of trigonal selenium, as the optoelectronic material properties are anisotropic. 14 The crystallographic orientation of the grains in the selenium thin-film is therefore expected to affect the PV device performance. The crystallization of amorphous selenium under the influence of light was first studied half a century ago, where it was observed that illumination increases the growth rate of crystallites and modifies their external morphology.…”

Section: ■ Introductionmentioning

confidence: 99%

Laser-Annealing and Solid-Phase Epitaxy of Selenium Thin-Film Solar Cells

Nielsen,

Hemmingsen,

Bonczyk

et al. 2023

ACS Appl. Energy Mater.

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Selenium has resurged as a promising photovoltaic material in solar cell research due to its wide direct bandgap of 1.95 eV, making it a suitable candidate for a top cell in tandem photovoltaic devices. However, the optoelectronic quality of selenium thin-films has been identified as a key bottleneck for realizing high-efficiency selenium solar cells. In this study, we present an approach for crystallizing selenium thin-films using laser-annealing as an alternative to the conventionally used thermal annealing strategy. By laser-annealing through a semitransparent substrate, a buried layer of high-quality selenium crystallites is formed and used as a growth template for solid-phase epitaxy. The resulting selenium thin-films feature larger and more preferentially oriented grains with a negligible surface roughness in comparison to thermally annealed selenium thin-films. We fabricate photovoltaic devices using this strategy and demonstrate a record ideality factor of n = 1.37, a record fill factor of FF = 63.7%, and a power conversion efficiency of PCE = 5.0%. The presented laser-annealing strategy is universally applicable and is a promising approach for crystallizing a wide range of photovoltaic materials where high temperatures are needed while maintaining a low substrate temperature.

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Sustainable Recycling of Selenium‐Based Optoelectronic Devices

Wang,

Li,

Jin

et al. 2024

Advanced Science

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Selenium (Se), the world's oldest optoelectronic material, has been widely applied in various optoelectronic devices such as commercial X‐ray flat‐panel detectors and photovoltaics. However, despite the rare and widely‐dispersed nature of Se element, a sustainable recycling of Se and other valuable materials from spent Se‐based devices has not been developed so far. Here a sustainable strategy is reported that makes use of the significantly higher vapor pressure of volatile Se compared to other functional layers to recycle all of them from end‐of‐life Se‐based devices through a closed‐space evaporation process, utilizing Se photovoltaic devices as a case study. This strategy results in high recycling yields of ≈ 98% for Se and 100% for other functional materials including valuable gold electrodes and glass/FTO/TiO2 substrates. The refabricated photovoltaic devices based on these recycled materials achieve an efficiency of 12.33% under 1000‐lux indoor illumination, comparable to devices fabricated using commercially sourced materials and surpassing the current indoor photovoltaic industry standard of amorphous silicon cells.

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Origin of photovoltaic losses in selenium solar cells with open-circuit voltages approaching 1 V

Abstract: Research on selenium solar cells is regaining momentum due to the exciting prospect of integrating a single-element, wide-bandgap (≈1.95 eV) photoabsorber in tandem with a lower bandgap photovoltaic device. Low...

Cited by 17 publications

References 52 publications

Selenium Thin-Film Solar Cells with Cadmium Sulfide as a Heterojunction Partner

Selenium Thin-Film Solar Cells with Cadmium Sulfide as a Heterojunction Partner

Laser-Annealing and Solid-Phase Epitaxy of Selenium Thin-Film Solar Cells

Sustainable Recycling of Selenium‐Based Optoelectronic Devices

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