Fabrication of monolithic CZTS/Si tandem cells by development of the intermediate connection

Valentini, Matteo; Malerba, Claudia; Serenelli, L.; Izzi, M.; Salza, E.; Tucci, M.; Mittiga, A.

doi:10.1016/j.solener.2019.08.029

Cited by 39 publications

(38 citation statements)

References 22 publications

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“…3 In order to achieve functional CZTS/Si monolithic devices, it has been suggested that strategies for protecting the bottom Si cell need to be developed. [3][4][5] In this work, we approach this problem through a comparative study of CZTS/Si tandem cells fabricated using three different types of TiN-based diffusion barrier layers. For the first and second, we use atomic layer deposition (ALD) to produce 5 and 10 nm TiN barrier layers, and a 10 nm TiOxNy barrier layer.…”

Section: Introductionmentioning

confidence: 99%

Nitride-Based Interfacial Layers for Monolithic Tandem Integration of New Solar Energy Materials on Si: The Case of CZTS

Martinho

Hajijafarassar

López-Mariño

et al. 2020

ACS Appl. Energy Mater.

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The monolithic tandem integration of third-generation solar energy materials on silicon holds great promise for photoelectrochemistry and photovoltaics. However, this can be challenging when it involves high-temperature reactive processes, which would risk damaging the Si bottom cell. One such case is the high-temperature sulfurization/selenization in thin film chalcogenide solar cells, of which the kesterite Cu2ZnSnS4 (CZTS) is an example. Here, by using very thin (<10 nm) TiN-based diffusion barriers at the interface, with different composition and properties, we demonstrate on a device level that the protection of the Si bottom cell is largely dependent on the barrier layer engineering. Several monolithic CZTS/Si tandem solar cells with open-circuit voltages (Voc) up to 1.06 V and efficiencies up to 3.9% are achieved, indicating a performance comparable to conventional interfacial layers based on transparent conductive oxides, and pointing to a promising alternative design in solar energy conversion devices.

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Section: Introductionmentioning

confidence: 99%

Nitride-Based Interfacial Layers for Monolithic Tandem Integration of New Solar Energy Materials on Si: The Case of CZTS

Martinho

Hajijafarassar

López-Mariño

et al. 2020

ACS Appl. Energy Mater.

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“…This behavior, different to those observed both for SnO 2 20 and ZnO 28 can be explained by the following mechanism: the F atoms preferably replace O in the stoichiometric zone of SnO 2 which explains the reduction of the low energy peak width and the formation of O vacancies due to induced lattice distortion 20 . At higher SF 6…”

mentioning

confidence: 98%

Sputtered ZnSnO Buffer Layers for Kesterite Solar Cells

Grenet

Emieux

Andrade‐Arvizu

et al. 2020

ACS Appl. Energy Mater.

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Replacing the CdS buffer layer with a ZnSnO one in Cu 2 ZnSnS 4 -based solar cells allows both to improve the device performances and to avoid using toxic Cd. Additionally, using a sputtered buffer layer is a major asset for solar cells fabricated by physical vapor deposition processes. In this study, ZnSnO layers are deposited by sputtering of a single metal-oxide target. Structural and optical properties of the layers deposited on Si or glass are first described. The possibility of modifying the ZnSnO metallic composition by adjusting the deposition power is demonstrated. Attempts to improve the optoelectronic properties of the ZnSnO layers with Ar:O 2 or Ar:SF 6 reactive sputtering are shown as well. These ZnSnO buffer layers are transferred in Mo/CZTS/ZnSnO/ZnO:Al solar cells. After post-deposition thermal treatment and optimization of the deposition condition (notably with the use of Ar:O 2 or Ar:SF 6 reactive sputtering), a solar cells with a power conversion efficiency of 5.2% is demonstrated. It is 0.6% absolute higher than the reference solar cell with a CdS buffer layer. To avoid absorber damaging and achieve high performances, deposition power must be as low as possible. A two stages sputtering process is used to conciliate both the absorber surface preservation and a reasonable deposition time. Last, photovoltaic properties of optimized CZTS-and CZTSe-based solar cells with ZnSnO buffer layers are compared.

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“…[7,8] Moreover, pure-sulfide CZTS is also one of the most promising candidates as the top cell for silicon-based tandem solar cells, potentially triggering further technological evolution for largescale deployment of PV technologies. [9][10][11] Nevertheless, the current status of CZTS thin-film solar cells suffers from a much more open-circuit voltage (V OC ) loss than low-bandgap Cu 2 ZnSnS,Se 4 (CZTSSe) solar cells. [3,12,13] Besides the more severe bandgap/potential fluctuation and shorter photoluminescence (PL) decay time (related to real minority carrier lifetime), [14][15][16] the unfavorable "cliff"-like conduction band offset (CBO) at CZTS/CdS heterojunction interface is well believed to be a serious limiting factor to the V OC of CZTS solar cells.…”

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confidence: 99%

Interface Recombination of Cu₂ZnSnS₄ Solar Cells Leveraged by High Carrier Density and Interface Defects

Huang

et al. 2021

Solar RRL

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Pure-sulfide kesterite Cu 2 ZnSnS 4 (CZTS)-based thin-film solar cell has been emerging as a promising cost-effective thin-film photovoltaic (PV) technology, enjoying its Earth-abundant and ecofriendly constituents, thermodynamically stable structure, combined with the ideal bandgap perfectly matching with solar spectrum, and the compatibility with both rigid and flexible substrates. [1][2][3][4][5][6] These compelling features endow this PV technology huge potential for application of various scenes in the future, including wearable and portable PV power sources, building-integrated PVs (BIPVs) at curved building surfaces, and sustainable power sources for internet of things (IOT). [7,8] Moreover, pure-sulfide CZTS is also one of the most promising candidates as the top cell for silicon-based tandem solar cells, potentially triggering further technological evolution for largescale deployment of PV technologies. [9][10][11] Nevertheless, the current status of CZTS thin-film solar cells suffers from a much more open-circuit voltage (V OC ) loss than low-bandgap Cu 2 ZnSnS,Se 4 (CZTSSe) solar cells. [3,12,13] Besides the more severe bandgap/potential fluctuation and shorter photoluminescence (PL) decay time (related to real minority carrier lifetime), [14][15][16] the unfavorable "cliff"-like conduction band offset (CBO) at CZTS/CdS heterojunction interface is well believed to be a serious limiting factor to the V OC of CZTS solar cells. [17][18][19][20] To address this issue, alternative buffer materials with wide bandgap and a suitable conduction band edge have been screened, among which (Zn,Cd)S and (Zn,Sn)O are the most successful materials, allowing a great V OC boost up to 100 mV. [18,19] Nevertheless, the V OC of CZTS solar cells with a bandgap of 1.5 eV is still limited to be below 750 mV, far lower than that of the moderate CdTe solar cells with a similar recombination bandgap (1.45 eV) and low minority carrier lifetime (1À2 ns), let alone the "cliff"-like CBO at the CdTe/CdS interface. [21][22][23][24] Results of SunsÀV OC measurements for these cells configured with (Zn,Sn)O or (Zn,Cd)S buffer layer have revealed that J 02 (representing nonradiative recombination at the heterojunction region) is still 5 orders of magnitude larger than J 01 (representing nonradiative recombination in the quasineutral bulk region) (10 À7 A cm À2 for J 02 vs. 10 À12 A cm À2 for J 01 ). [18,19] This verifies that the V OC of pure-sulfide CZTS solar cells is still currently limited by nonradiative recombination in the heterojunction interface region, even though the unfavorable "cliff-like" CBO has been avoided, indicating that other important interface recombination mechanisms may persist and are yet to be properly recognized.

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Fabrication of monolithic CZTS/Si tandem cells by development of the intermediate connection

Cited by 39 publications

References 22 publications

Nitride-Based Interfacial Layers for Monolithic Tandem Integration of New Solar Energy Materials on Si: The Case of CZTS

Nitride-Based Interfacial Layers for Monolithic Tandem Integration of New Solar Energy Materials on Si: The Case of CZTS

Sputtered ZnSnO Buffer Layers for Kesterite Solar Cells

Interface Recombination of Cu₂ZnSnS₄ Solar Cells Leveraged by High Carrier Density and Interface Defects

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Fabrication of monolithic CZTS/Si tandem cells by development of the intermediate connection

Cited by 39 publications

References 22 publications

Nitride-Based Interfacial Layers for Monolithic Tandem Integration of New Solar Energy Materials on Si: The Case of CZTS

Nitride-Based Interfacial Layers for Monolithic Tandem Integration of New Solar Energy Materials on Si: The Case of CZTS

Sputtered ZnSnO Buffer Layers for Kesterite Solar Cells

Interface Recombination of Cu2ZnSnS4 Solar Cells Leveraged by High Carrier Density and Interface Defects

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Interface Recombination of Cu₂ZnSnS₄ Solar Cells Leveraged by High Carrier Density and Interface Defects