Cu2ZnSnS4 solar cells with over 10% power conversion efficiency enabled by heterojunction heat treatment

Yan, Chang; Huang, Jialiang; Sun, Kaiwen; Johnston, Steve; Zhang, Yuanfang; Sun, Heng; Pu, Aobo; He, Mingrui; Liu, Fangyang; Eder, Katja; Yang, Limei; Cairney, Julie M.; Ekins-Daukes, N. J.; Hameiri, Ziv; Stride, John A.; Chen, Shiyou; Green, Martin A.; Hao, Xiaojing

doi:10.1038/s41560-018-0206-0

Cited by 716 publications

(550 citation statements)

References 46 publications

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“…Comparison of the d(−ln(1 − EQE))/dE versus E plot for Cu/ [Cd+Sn] = 0.80 with the data extracted from currently published record Cu 2 ZnSnS 4 , [42] Cu 2 ZnSn(S,Se) 4 , [3] and Cu 2 ZnSnSe 4 [43] based devices ( Figure S13a, Supporting Information) shows that Cu 2 CdSnS 4 has smaller bandgap fluctuations than the record devices. Furthermore, comparing the corresponding data from various publications ( Figure S13b,c, Supporting Information), [3,7,9,[42][43][44] which include high-efficiency devices for Ag-, Cd-, Ge-, and Ba-alloyed absorbers, only Ba-alloyed absorbers have smaller bandgap fluctuations than Cu 2 CdSnS 4 ( Figure S13c, Supporting Information).…”

Section: Bandgap and Bandgap Fluctuationsmentioning

confidence: 97%

“…[12] This might also be one of the reasons for the decreasing trend in the J SC /J SC,SQ values for the record kesterite devices with increasing S/Se ratio: the 11.6% Cu 2 ZnSnSe 4 , [43] 12.6% Cu 2 ZnSn(S,Se) 4 , [3] and 11.01% Cu 2 ZnSnS 4 [42] devices achieved J SC /J SC,SQ equal to 84.2%, 81.6%, and 74.9%, respectively. Hence, further improvements in the J SC for Cu 2 ZnSnS 4 should focus on the improvement of minority carrier lifetime.…”

Section: Current-voltage Characteristicsmentioning

confidence: 98%

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Suppressed Deep Traps and Bandgap Fluctuations in Cu₂CdSnS₄ Solar Cells with ≈8% Efficiency

Hadke

Levcenko

Gautam

et al. 2019

Advanced Energy Materials

119

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postdeposition alkali treatment to improve heterojunction diode quality in Cu(In,Ga) Se 2 (CIGS) solar cells and chloride treatment to passivate grain boundaries in CdTe solar cells. [1] These solar-cell technologies are already commercialized, with lab-scale photovoltaic efficiencies exceeding 22%. [2] However, kesterite-based solar cells, such as Cu 2 ZnSn(S,Se) 4 , which share many of the same characteristics of CIGS and CdTe, significantly lag behind, with a record power conversion efficiency (PCE) of 12.6%. [3] Although the dominant limiting factors for this low performance are a matter of considerable discussion, [4] the following observations are consistent among kesterite absorbers: i) a low photoluminescence quantum yield (PLQY) and a short chargecarrier lifetime, [5] ii) a high value of Urbach band tail energy (larger than 30 meV for S-rich kesterites) and lack of a steep absorption onset, [6,7] and iii) the presence of secondary phases. [4,6,8,9] The extent to which these factors individually affect the photovoltaic performance is debated, but their ubiquity among kesterite absorbers indicates the presence of a large density of point defects. [10][11][12] Specifically, i) the low PLQY arises from the presence of nonradiative mid-gap The identification of performance-limiting factors is a crucial step in the development of solar cell technologies. Cu 2 ZnSn(S,Se) 4 -based solar cells have shown promising power conversion efficiencies in recent years, but their performance remains inferior compared to other thin-film solar cells. Moreover, the fundamental material characteristics that contribute to this inferior performance are unclear. In this paper, the performance-limiting role of deep-trap-level-inducing 2Cu Zn +Sn Zn defect clusters is revealed by comparing the defect formation energies and optoelectronic characteristics of Cu 2 ZnSnS 4 and Cu 2 CdSnS 4 . It is shown that these deleterious defect clusters can be suppressed by substituting Zn withCd in a Cu-poor compositional region. The substitution of Zn with Cd also significantly reduces the bandgap fluctuations, despite the similarity in the formation energy of the Cu Zn +Zn Cu and Cu Cd +Cd Cu antisites. Detailed investigation of the Cu 2 CdSnS 4 series with varying Cu/[Cd+Sn] ratios highlights the importance of Cu-poor composition, presumably via the presence of V Cu , in improving the optoelectronic properties of the cation-substituted absorber. Finally, a 7.96% efficient Cu 2 CdSnS 4 solar cell is demonstrated, which shows the highest efficiency among fully cation-substituted absorbers based on Cu 2 ZnSnS 4 .

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Section: Bandgap and Bandgap Fluctuationsmentioning

confidence: 97%

Section: Current-voltage Characteristicsmentioning

confidence: 98%

Suppressed Deep Traps and Bandgap Fluctuations in Cu₂CdSnS₄ Solar Cells with ≈8% Efficiency

Hadke

Levcenko

Gautam

et al. 2019

Advanced Energy Materials

119

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“…The highest laboratory efficiencies, 22.6 and 22.1%, have been reported for CIGS and CdTe solar cells, respectively. Recently, a Cu 2 ZnSnS 4 (CZTS) cell with a laboratory efficiency reaching 11.1% has been reported . Because of the complexity of the components and the difficult process control of CIGS and CZTS, many efforts have been directed toward finding low‐cost materials that used earth‐abundant and environmentally friendly elements.…”

Section: Introductionmentioning

confidence: 99%

Enhancement in the Efficiency of Sb₂Se₃ Thin‐Film Solar Cells by Increasing Carrier Concertation and Inducing Columnar Growth of the Grains

et al. 2018

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Antimony selenide (Sb2Se3) thin films are attractive light‐absorbing materials for low‐cost and highly efficient thin‐film solar cells. Optimizing columnar growth of the grains and the proper hole concentration will be very helpful for improving the efficiency of Sb2Se3 thin‐film solar cells. In this paper, a monoatomic layer of Al2O3 prepared by the atomic layer deposition (ALD) method is used to increase the hole concentration of the Sb2Se3 film. The increase in the hole concentration is mainly due to the suppression of n‐type defects, such as Vse, or the increase in p‐type defects, such as Vsb. In addition, a simple and environmentally friendly oxygen plasma method is used to modify the CdS film to induce ordered columnar growth of the Sb2Se3 film deposited by the rapid thermal evaporation (RTE) method. Finally, an oxygen plasma treatment on CdS and a monoatomic Al2O3 layer covering the Sb2Se3 was combined to fabricate a solar cell with a new structure, FTO/CdS/P‐Sb2Se3/P+‐Sb2Se3/Al2O3/Au, and its efficiency was increased from 2.48% to 6.7%. These simple, nontoxic, and industrially applicable methods provide potential avenues for preparing low‐cost and highly efficient solar cells.

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“…Kesterite Cu 2 ZnSnS 4 (CZTS) semiconductor has drawn considerable attention as an active light absorber layer for thin‐film solar cells since it possesses a number of unique properties: i) all the compositional elements are earth‐abundant and non‐toxic; ii) it has a direct bandgap (≈1.5 eV) that is close to the optimal bandgap for single‐junction solar cells according to the Shockley–Queisser limit; iii) it has a large light absorption coefficients (>10 4 cm −1 ); and iv) it has similar electronic structures and optical properties to Cu(In,Ga)Se 2 (CIGS), which has demonstrated a light‐to‐electricity power conversion efficiency (PCE) of over 22% . Despite the above advantages, the reported best PCE of pure CZTS thin‐film solar cells has just reached ≈11%, far below the theoretical limit and the commercialization requirement. The achieved PCE by co‐evaporation/sulfurization process is even lower (8.4%) .…”

Section: Introductionmentioning

confidence: 99%

Modification of Mo Back Contact with MoO_3−x Layer and its Effect to Enhance the Performance of Cu₂ZnSnS₄ Solar Cells

et al. 2018

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Kesterite Cu2ZnSnS4 (CZTS) has been investigated intensively as a promising absorber material for thin film solar cells. However, the reported best power conversion efficiency (PCE) is still low due to the intrinsic limitations of CZTS defects and the unfavorable front and back contact interfaces. In this study, an intermediate MoO3−x layer is introduced as a primary back contact prior to the Cd‐doped Cu2ZnSnS4 (CZCTS) absorber layer growth. It has been demonstrated that the insertion of the MoO3−x layer can suppress the decomposition reaction between CZCTS and Mo, reducing secondary phases and voids and improving the rear interface quality. The MoO3−x layer can also accelerate potassium diffusion into the CZCTS layer and interfaces, which facilitates the grain growth, passivates interfaces and hence yields better crystallinity. Moreover, the band alignment at the back contact is modified by the MoO3−x layer, resulting in better minority carrier collection and improvement of open‐circuit voltage (VOC). With the optimal MoO3−x layer, the PCE of CZCTS solar cells has increased from ≈5.43 to ≈7%, largely attributed to the ≈60 mV VOC increment. Through the modification of the CZCTS precursor and optimizing the anti‐reflection coating layer, the best PCE achieved is 8.98%, with an active area efficiency of 9.26%.

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Cu2ZnSnS4 solar cells with over 10% power conversion efficiency enabled by heterojunction heat treatment

Cited by 716 publications

References 46 publications

Suppressed Deep Traps and Bandgap Fluctuations in Cu₂CdSnS₄ Solar Cells with ≈8% Efficiency

Suppressed Deep Traps and Bandgap Fluctuations in Cu₂CdSnS₄ Solar Cells with ≈8% Efficiency

Enhancement in the Efficiency of Sb₂Se₃ Thin‐Film Solar Cells by Increasing Carrier Concertation and Inducing Columnar Growth of the Grains

Modification of Mo Back Contact with MoO_3−x Layer and its Effect to Enhance the Performance of Cu₂ZnSnS₄ Solar Cells

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Cu2ZnSnS4 solar cells with over 10% power conversion efficiency enabled by heterojunction heat treatment

Cited by 716 publications

References 46 publications

Suppressed Deep Traps and Bandgap Fluctuations in Cu2CdSnS4 Solar Cells with ≈8% Efficiency

Suppressed Deep Traps and Bandgap Fluctuations in Cu2CdSnS4 Solar Cells with ≈8% Efficiency

Enhancement in the Efficiency of Sb2Se3 Thin‐Film Solar Cells by Increasing Carrier Concertation and Inducing Columnar Growth of the Grains

Modification of Mo Back Contact with MoO3−x Layer and its Effect to Enhance the Performance of Cu2ZnSnS4 Solar Cells

Contact Info

Product

Resources

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Suppressed Deep Traps and Bandgap Fluctuations in Cu₂CdSnS₄ Solar Cells with ≈8% Efficiency

Suppressed Deep Traps and Bandgap Fluctuations in Cu₂CdSnS₄ Solar Cells with ≈8% Efficiency

Enhancement in the Efficiency of Sb₂Se₃ Thin‐Film Solar Cells by Increasing Carrier Concertation and Inducing Columnar Growth of the Grains

Modification of Mo Back Contact with MoO_3−x Layer and its Effect to Enhance the Performance of Cu₂ZnSnS₄ Solar Cells