Effective Surface Treatment for High-Performance Inverted CsPbI2Br Perovskite Solar Cells with Efficiency of 15.92%

Fu, Sheng-Quan; Li, Xiaodong; Wan, Li; Zhang, Wenxiao; Song, Weijie

doi:10.1007/s40820-020-00509-y

Cited by 46 publications

(36 citation statements)

References 55 publications

(69 reference statements)

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“…[7,23] Very recently, well-designed polymer poly [3-(4-carboxylbutyl)thiophene methylamine] and small molecule 4,4′,4″,4′″-(ethene-1,1,2,2-tetrayl)tetrakis(N,N-bis(4-(methylthio)phenyl)aniline) (TPE-S) have been employed as the underlayer and hole transport layer (HTL) for inverted inorganic PeSCs, which afford excellent device performance with record PCEs. [24,25] Nevertheless, these hole transport materials (HTMs) are lab-synthesized and not commercially available, which limits their wide applications. The new underlayer as well as HTL based on ingenious design with commercially available materials is highly desired.…”

Section: Introductionmentioning

confidence: 99%

Managing Defects Density and Interfacial Strain via Underlayer Engineering for Inverted CsPbI₂Br Perovskite Solar Cells with All‐Layer Dopant‐Free

Han

Yuan

et al. 2021

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Inorganic perovskite CsPbI2Br has advantages of excellent thermal stability and reasonable bandgap, which make it suitable for top layer of tandem solar cells. Nevertheless, solution‐processed all‐inorganic perovskites generally suffer from high‐density defects as well as significant tensile strain near underlayer/perovskite interface, both leading to compromised device efficiency and stability. In this work, the defect density as well as interfacial tensile strain in inverted CsPbI2Br perovskite solar cells (PeSCs) is remarkably reduced by using a bilayer underlayer composed of dopant‐free 2,2′,7,7′‐tetrakis(N,N‐dip‐methoxyphenylamine)‐9,9′‐spirobifluorene (Spiro‐OMeTAD) and copper phthalocyanine 3,4′,4″,4′″‐tetrasulfonated acid tetrasodium salt (TS‐CuPc) nanoparticles. As compared to control devices with pristine Spiro‐OMeTAD, devices based on Spiro‐OMeTAD/TS‐CuPc exhibit remarkably improved photovoltaic performance and enhanced thermal/humidity stability due to the better perovskite crystallization, improved interfacial passivation, and hole‐collection as well as efficient interfacial strain release. As a result, a champion efficiency of 14.85% can be achieved, which is approaching to the best reported for dopant‐free and inverted all‐inorganic PeSCs. The work thus provides an efficient strategy to simultaneously regulate the defects density and strain issue related to inorganic perovskites.

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Section: Introductionmentioning

confidence: 99%

Managing Defects Density and Interfacial Strain via Underlayer Engineering for Inverted CsPbI₂Br Perovskite Solar Cells with All‐Layer Dopant‐Free

Han

Yuan

et al. 2021

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“…The result verifies the BTEC‐2F to be an effective hole‐conductor. On top of that, the PL peak experiences a blue shift by 4 nm after BTEC‐2F treatment, which implies the suppressed non‐radiative in‐gap states in CsPbI 2 Br/BTEC‐2F film 24 . And this stems from the passivated trap state as evidenced by XPS results.…”

Section: Resultsmentioning

confidence: 89%

Improved phase stability of CsPbI₂Br perovskite by released microstrain toward highly efficient and stable solar cells

Zheng

Liu

et al. 2021

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All‐inorganic perovskite solar cells (PSCs) have developed rapidly in the field of photovoltaics due to their excellent thermal and light stability. However, compared with organic–inorganic hybrid perovskites, the phase instability of inorganic perovskite under humidity still remains as a critical issue that hampers the commercialization of inorganic PSCs. We originally propose in this work that microstrains between the perovskite lattices/grains play a key role in affecting the phase stability of inorganic perovskite. To this end, we innovatively design the π‐conjugated p‐type molecule bis(2‐ethylhexyl) 3,3′((4,8‐bis(5‐(2‐ethylhexyl)‐3,4‐difluorothiophen‐2‐yl)benzo[1,2‐b:4,5‐b′]dithiophene‐2,6‐diyl)bis(3,3″‐dioctyl[2,2′:5′,2″‐terthiophene]‐5″,5‐diyl))(2E,2′E)‐bis(2‐cyanoacrylate) (BTEC‐2F) to covalent with the Pb dangling bonds in CsPbI2Br perovskite film, which significantly suppress the trap states and release the defect‐induced local stress between perovskite grains. The interplay between the microstrains and phase stability of the inorganic perovskite are scrutinized by a series of characterizations including x‐ray photoelectron spectroscopy, photoluminescence, x‐ray diffraction, scanning electron microscopy, and so forth, based on which, we conclude that weaker local stresses in the perovskite film engender superior phase stability by preventing the perovskite lattice distortion under humidity. By this rational design, PSCs based on CsPbI2Br perovskite system deliver an outstanding power conversion efficiency (PCE) up to 16.25%. The unencapsulated device also exhibits an exceptional moisture stability by retaining over 80% of the initial PCE after 500 h aging in ambient with relative humidity of (RH) 25%.

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“…To date, champion PCEs of 17.03% and 15.92% have been achieved for n–i–p‐type (normal) and p–i–n (inverted)‐type PeSCs, respectively, both based on CsPbI 2 Br. [ 12–18 ] Nevertheless, such PCE values are still lower than those of hybrid PeSCs. Further improvement is highly demanded for all‐inorganic PeSCs.…”

Section: Introductionmentioning

confidence: 94%

Enhancing Built‐In Electric Field and Defect Passivation through Gradient Doping in Inverted CsPbI₂Br Perovskite Solar Cells

et al. 2020

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Organic/inorganic hybrid perovskite solar cells (PeSCs) have been of great interest due to their easy fabrication and high power conversion efficiency (PCE) exceeding 25%. [1-4] Nevertheless, hybrid perovskites (PVKs) suffer from low thermal stability due to the volatile nature of organic cations (i.e., methylamine), [5] which limits the commercial applications of hybrid PeSCs. [6,7] Thus, inorganic cations such as Cs þ are used to replace organic cations, [8] yielding all-inorganic PVKs with considerably improved thermal stability. [9,10] Among various Cs-based inorganic PVKs, dual-halide PVKs of CsPbI 2 Br feature a suitable bandgap (E g) of around 1.9 eV and reasonable phase stability, [11] which make it a promising photoabsorber. To date, champion PCEs of 17.03% and 15.92% have been achieved for n-i-p-type (normal) and p-in (inverted)-type PeSCs, respectively, both based on CsPbI 2 Br. [12-18] Nevertheless, such PCE values are still lower than those of hybrid PeSCs. Further improvement is highly demanded for all-inorganic PeSCs. It has been well recognized that solution-processed inorganic PVK films, especially those prepared at a low temperature, are highly defective, [19] which usually result in large energy loss in PeSCs. For example, the highest reported open-circuit voltages (V OC) are 1.40 and 1.27 V for normal and inverted CsPbI 2 Br PeSCs, [15,16] respectively, both much lower than the E g (%1.9 eV) of PVK. Such large energy loss might be attributed to the severe defect-induced nonradiative recombination. [20,21] In addition, high-density interfacial defects also lead to poor contact between the PVK and electrode, which increases device series resistance and reduces short-circuit current density (J SC) and fill factor (FF). [21] To minimize the bulk and interfacial defects associated with inorganic PVKs, a variety of passivation strategies have been used, [21-28] including additive engineering and post-treatment. Nevertheless, most strategies focus on the passivation of either bulk or interfacial defects rather than both. On the other hand, considerable efforts have been devoted to maximizing the built-in electric field (BEF) of PeSCs, which facilitates carrier separation/transport and hence contributes to the V OC of the device. As the BEF is primarily determined by the work function difference between the two electrodes or transport layers (i.e., electron transport layer [ETL] and hole transport layer [HTL]), [29] BEF enhancement still remains

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Effective Surface Treatment for High-Performance Inverted CsPbI2Br Perovskite Solar Cells with Efficiency of 15.92%

Cited by 46 publications

References 55 publications

Managing Defects Density and Interfacial Strain via Underlayer Engineering for Inverted CsPbI₂Br Perovskite Solar Cells with All‐Layer Dopant‐Free

Managing Defects Density and Interfacial Strain via Underlayer Engineering for Inverted CsPbI₂Br Perovskite Solar Cells with All‐Layer Dopant‐Free

Improved phase stability of CsPbI₂Br perovskite by released microstrain toward highly efficient and stable solar cells

Enhancing Built‐In Electric Field and Defect Passivation through Gradient Doping in Inverted CsPbI₂Br Perovskite Solar Cells

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Effective Surface Treatment for High-Performance Inverted CsPbI2Br Perovskite Solar Cells with Efficiency of 15.92%

Cited by 46 publications

References 55 publications

Managing Defects Density and Interfacial Strain via Underlayer Engineering for Inverted CsPbI2Br Perovskite Solar Cells with All‐Layer Dopant‐Free

Managing Defects Density and Interfacial Strain via Underlayer Engineering for Inverted CsPbI2Br Perovskite Solar Cells with All‐Layer Dopant‐Free

Improved phase stability of CsPbI2Br perovskite by released microstrain toward highly efficient and stable solar cells

Enhancing Built‐In Electric Field and Defect Passivation through Gradient Doping in Inverted CsPbI2Br Perovskite Solar Cells

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Product

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Managing Defects Density and Interfacial Strain via Underlayer Engineering for Inverted CsPbI₂Br Perovskite Solar Cells with All‐Layer Dopant‐Free

Managing Defects Density and Interfacial Strain via Underlayer Engineering for Inverted CsPbI₂Br Perovskite Solar Cells with All‐Layer Dopant‐Free

Improved phase stability of CsPbI₂Br perovskite by released microstrain toward highly efficient and stable solar cells

Enhancing Built‐In Electric Field and Defect Passivation through Gradient Doping in Inverted CsPbI₂Br Perovskite Solar Cells