Reduction of Trap and Polydispersity in Mutually Passivated Quantum Dot Solar Cells

Sharma, Ashish; Mahajan, Chandan; Rath, Arup K.

doi:10.1021/acsaem.0c01378

Cited by 9 publications

(7 citation statements)

References 50 publications

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“…However, an increase in CPT concentrations beyond 10 mM does not yield higher lifetime values for the photogenerated carriers. The density of trap states in the solar cells determined from the reported transient photovoltage and transient current decay measurements ,, shows a similar trend (Figure S7b). The −I passivated solar cells show higher trap densities than hybrid passivated solar cells; however, there is no noticeable decrease in trap densities for higher CPT concentrations.…”

Section: Results and Discussionsupporting

confidence: 55%

“…The density of trap states (DOS) is determined using the reported TPV and TPC methods. ,, By integrating the area under a TPC curve, the number of charge carriers generated by the light pulse is calculated. The differential capacitance is determined using the formula , where Δ q is the number of photogenerated carriers (determined from the TPC curve) and Δ V oc is the corresponding change in V oc due to the light pulse.…”

Section: Methodsmentioning

confidence: 99%

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Reduction of Hydroxyl Traps and Improved Coupling for Efficient and Stable Quantum Dot Solar Cells

Mandal

Dambhare

Rath

2021

ACS Appl. Mater. Interfaces

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Progress in quantum dot (QD)-based solar cells has been underpinned by the improvements in surface passivation and advancements in device engineering. Acute control over the surface properties is crucial to restrict the formation of in-gap trap states and improve the QD coupling in achieving conducting QD films. In this report, we demonstrate a solution-phase hybrid passivation strategy, which is beneficial in removing detrimental hydroxyl traps and improving the coupling between QDs by reducing the interdot distance. Advancement in surface passivation is translated to the long carrier lifetime, higher carrier mobility, and superior protection toward degradations in QD solids. The performance of solar cell devices is increased by 26% to reach an efficiency of 10.6%, compared to the state-of-the-art lead halide passivated solar cells. The improvement in solar cell performance is supported by the reduction of trap states and an 80 nm increase in thickness of the light-absorbing QD layer.

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Section: Results and Discussionsupporting

confidence: 55%

Section: Methodsmentioning

confidence: 99%

Reduction of Hydroxyl Traps and Improved Coupling for Efficient and Stable Quantum Dot Solar Cells

Mandal

Dambhare

Rath

2021

ACS Appl. Mater. Interfaces

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“…With the n-i-p structure, the CQDSC with hybrid ligands can achieve a V oc of 0.61 V, which is 40 mV higher than that with single iodide ligands (improved by 7%), and the V oc loss reaches ≈0.52 V. Additionally, Sargent group [66] proposed to treat CQD surface with organic ligands to prepare p-type CQD via hybrid passivation. With n-i-p structure, the CQDSC with hybrid ligands (p-type CQD) can achieve a V oc of 0.68 V, which is 50 mV higher than that with single halide ligands (improved by 8.1%), and the V oc loss drops to ≈0.45 V. Similarly, Sharma et al [126] also performed the hybrid passivation (iodide and methyl mercapto propionate) to achieve lower CQD surface defect density and higher V oc , indicating the robustness of this strategy. The CQDSC performance with different ligands is summarized in Table 3.…”

Section: Direct Passivationmentioning

confidence: 89%

“…With n–i–p structure, the CQDSC with hybrid ligands (p‐type CQD) can achieve a V oc of 0.68 V, which is 50 mV higher than that with single halide ligands (improved by 8.1%), and the V oc loss drops to ≈0.45 V. Similarly, Sharma et al. [ 126 ] also performed the hybrid passivation (iodide and methyl mercapto propionate) to achieve lower CQD surface defect density and higher V oc , indicating the robustness of this strategy. The CQDSC performance with different ligands is summarized in Table 3 .…”

Section: Solar Absorbermentioning

confidence: 92%

Open‐Circuit Voltage Loss in Lead Chalcogenide Quantum Dot Solar Cells

Liu

Xian

et al. 2021

Advanced Materials

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absorption coefficients, which can be used to capture the far-infrared of solar radiation. [13,14] This outperforms silicon-based and other solution-based semiconductor materials. Additionally, lead chalcogenide CQDSCs have the potential to break through the Shockley-Quesser limit, via multiple exciton generation. [15][16][17][18] In the past decade, lead chalcogenide CQDSCs have attracted abundant attention and their power conversion efficiencies (PCEs) have increased from ≈3% to ≈14%. [19][20][21] Moreover, the facile solution-processability (synthesis and ligand exchange) allows the production of solar cells by spraying, scraping, and roll-to-roll process, enabling great commercial potential. [22][23][24][25] Recently, some reports discussed the commercial viability of lead chalcogenide CQDSCs. [26,27] The results demonstrated that the cost of flexible lead chalcogenide CQDSCs can be as low as ≈0.94 $ per W, indicating the strong competitiveness of these solution-processability solar cells. To reach this low production cost, the PCEs of the CQDSCs are assumed to be 19% and the devices are assumed to be manufactured via a roll-toroll process. [27] Thus, it is still a great challenge for the commercialization of lead chalcogenide CQDSCs, and the low PCE is still the main obstacle for its market competitiveness.We summarize the main developments of lead chalcogenide CQDSCs (see Figure 1). In the early stage, the Schottky structure was used and it achieved the highest PCE of ≈5.2% in 2013. [28] But after 2014, there exist few reports of lead chalcogenide CQDSCs with the Schottky structure, due to the mismatch between optical absorption and charge extraction. [29] Subsequently, the n-p structure and depleted bulk heterojunction (DBH) structure have greatly improved the PCEs of lead chalcogenide CQDSCs. [30,31] N-p structure uses p-n junction to improve carrier extraction efficiency and reduce recombination, thus increasing the PCE of lead chalcogenide CQDSCs from ≈3% to above 9% in 2015. [19,32] Additionally, the absorption coefficient of lead chalcogenide CQDSCs reaches ≈10 6 cm −3 , which means that it is essential to use ≈1 μm solar absorber to fully absorb solar radiation. The DBH structure uses a bulk electron transport layer (ETL) to address the challenge of insufficient carrier diffusion length for the n-p structure, thus increasing the absorber thickness and greatly improving the short-circuit current (J sc ). [33][34][35] Through continued efforts, the PCE of the DBH structure has reached ≈10.8%. [36] To date, more research Lead chalcogenide colloidal quantum dot solar cells (CQDSCs) have received considerable attention due to their broad and tunable absorption and high stability. Presently, lead chalcogenide CQDSC has achieved a power conversion efficiency of ≈14%. However, the state-of-the-art lead chalcogenide CQDSC still has an open-circuit voltage (V oc ) loss of ≈0.45 V, which is significantly higher than those of c-Si and perovskite solar cells. Such high V oc loss severely limits the performance im...

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“…Sargent and co-workers found that PbI 3 – -shelled PbS nanocrystals allowed fabrication of nanocrystal solar cells with power conversion efficiencies of 8.95%, a major advancement for nanocrystal devices . Halometallate ligation has subsequently been employed in other nanocrystal optoelectronic devices. − …”

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confidence: 99%

Halometallates Bind as Z-Type Ligands on Wurtzite CdSe Nanoplatelets

Buhro

2022

Chem. Mater.

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Two-phase ligand exchange of amine-ligated, wurtzite, [CdSe(n-octylamine)0.43(oleylamine)0.07] nanoplatelets with ammonium salts (NH4Cl or [NH4]2[ZnCl4]) or the Lewis acids (ZnCl2 or CdCl2) in N-methylformamide/hexane afford NMF-ligated [CdSe(NMF)0.18(n-octylamine)0.09] nanoplatelets. Subsequent ligand exchanges with the intermediate NMF-ligated nanoplatelets give halometallate-ligated CdSe nanoplatelets having CdX3 – or ZnX4 2– ligands (X = Cl, Br, and I). Two-phase ligand exchange of [CdSe(n-octylamine)0.43(oleylamine)0.07] nanoplatelets with ammonium salts [NH4][CdX3] in N,N-dimethylformamide afford halometallate ligation directly. Analysis of the absorption spectra and X-ray diffraction data of the halometallate-ligated nanoplatelets establish that the halometallates bind as intact, Z-type ligands.

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Reduction of Trap and Polydispersity in Mutually Passivated Quantum Dot Solar Cells

Cited by 9 publications

References 50 publications

Reduction of Hydroxyl Traps and Improved Coupling for Efficient and Stable Quantum Dot Solar Cells

Reduction of Hydroxyl Traps and Improved Coupling for Efficient and Stable Quantum Dot Solar Cells

Open‐Circuit Voltage Loss in Lead Chalcogenide Quantum Dot Solar Cells

Halometallates Bind as Z-Type Ligands on Wurtzite CdSe Nanoplatelets

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