Introducing paired electric dipole layers for efficient and reproducible perovskite solar cells

Lee, Jong Hoon; Kim, Junghwan; Kim, Geunjin; Shin, Dongguen; Jeong, Song Yi; Lee, Jinho; Hong, Soon-Il; Choi, Jin Woo; Lee, Chang Lyoul; Kim, Hee Joo; Yi, Yeonjin; Lee, Kwanghee

doi:10.1039/c8ee00162f

Cited by 76 publications

(71 citation statements)

References 55 publications

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“…The UPS analysis (Figure S4a, Supporting Information) shows that the WF of PFN film coated with 10 nm thick Al is 2.8 eV, much lower than that of pure Al (4.3 eV). The large variation in WF of metals modified by PFN is good agreement with previous findings . A positive interface dipole can be formed (taking the dipole directed outward to be positive), generating a negative dipole potential for electrons.…”

Section: Resultssupporting

confidence: 91%

“…The schematic of flat‐band energy level diagram is shown in Figure c, and the energy level values for CsPbBr 3 ‐PEO and PFN were estimated by ultraviolet photoelectron spectroscopy (UPS) and optical measurements (Figure S3, Supporting Information), while the energy level values of ITO, PEDOT:PSS, and Al were taken from literatures . The PFN interlayer not only offers ohmic contact for charge transfer, but also produces dipoles at PFN/Al interfaces to reduce injection barriers . The UPS analysis (Figure S4a, Supporting Information) shows that the WF of PFN film coated with 10 nm thick Al is 2.8 eV, much lower than that of pure Al (4.3 eV).…”

Section: Resultsmentioning

confidence: 99%

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Efficient All‐Solution‐Processed Perovskite Light‐Emitting Diodes Enabled by Small‐Molecule Doped Electron Injection Layers

Zhang

Wang

Cao

et al. 2019

Advanced Optical Materials

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Metal halide perovskites have attracted considerable attention in the field of light‐emitting diodes due to their high color purity and solution processability. However, most perovskite light‐emitting diodes (PeLEDs) employ thermally deposited charge transport layers (CTLs) on top of perovskite layers. In order to realize low‐cost and scalable fabrication of PeLEDs, all‐solution process is highly desired, but still remaining great challenges. Here, an efficient all‐solution‐processed green PeLEDs is reported by incorporating 1,3,5‐tris(1‐phenyl‐1H‐benzimidazol‐2‐yl)benzene (TPBi) doped conjugated amino‐alkyl substituted polyfluorene poly[(9,9‐bis(3′‐(N,N‐dimethylamino)propyl)‐2,7‐fluorene)‐alt‐2,7‐(9,9‐dioctylfluorene)] (PFN) electron injection layer, achieving a maximum luminance of 9875 cd m−2, a high current efficiency of 10.41 cd A−1, and an external quantum efficiency of 3.19%. Since the solvents used for perovskite precursors and PFN are orthogonal, the protected and complete interface of perovskite film and CTL is effectively obtained by solution processes. The doping of TPBi into PFN not only enhances the capability of electron injection, but also significantly suppresses the emission quenching of perovskite films caused by the charge transfer between perovskite and PFN due to the reduced difference in their work functions. This work provides an efficient approach for the development of all‐solution‐processed PeLEDs.

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Section: Resultssupporting

confidence: 91%

Section: Resultsmentioning

confidence: 99%

Efficient All‐Solution‐Processed Perovskite Light‐Emitting Diodes Enabled by Small‐Molecule Doped Electron Injection Layers

Zhang

Wang

Cao

et al. 2019

Advanced Optical Materials

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“…Theoretically, the open voltage of PSCs mainly depended on the splitting of electron and hole quasi‐Fermi levels in the fabricated devices . Previous studies have shown that as for the 2D–3D perovskite stacking‐layered architecture, large‐bandgap 2D perovskite capping layer could induce larger Fermi‐level separation, in favor of the enhanced open‐circuit voltage .…”

Section: Resultsmentioning

confidence: 99%

Conjugated Molecules “Bridge”: Functional Ligand toward Highly Efficient and Long‐Term Stable Perovskite Solar Cell

Dong

Zuo

et al. 2019

Adv Funct Materials

107

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Interfacial ligand passivation engineering has recently been recognized as a promising avenue, contributing simultaneously to the optoelectronic characteristics and moisture/operation tolerance of perovskite solar cells. To further achieve a win-win situation of both performance and stability, an innovative conjugated aniline modifier (3-phenyl-2-propen-1-amine; PPEA) is explored to moderately tailor organolead halide perovskites films. Here, the conjugated PPEA presents both "quasi-coplanar" rigid geometrical configuration and distinct electron delocalization characteristics. After a moderate treatment, a stronger dipole capping layer can be formed at the perovskite/ transporting interface to achieve favorable banding alignment, thus enlarging the built-in potential and promoting charge extraction. Meanwhile, a conjugated cation coordinated to the surface of the perovskite grains/units can form preferably ordered overlapping, not only passivating the surface defects but also providing a fast path for charge exchange. Benefiting from this, a ≈21% efficiency of the PPEA-modified solar cell can be obtained, accompanied by long-term stability (maintaining 90.2% of initial power conversion efficiency after 1000 h testing, 25 °C, and 40 ± 10 humidity). This innovative conjugated molecule "bridge" can also perform on a larger scale, with a performance of 18.43% at an area of 1.96 cm 2 .

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“…Recent progresses also indicated that the enhanced built‐in electric field (BEF) would significantly raise the oriented charge transfer to further improve the photovoltaic performance of a PSC. In particular, Lee et al [ 25 ] demonstrated that increasing the difference of work functions (WFs) between two electrodes can reinforce the driving force and obtain a power‐conversion efficiency (PCE) of 19.4%. Li et al [ 26 ] prepared a homojunction perovskite to induce p‐type or n‐type doping, which promoted the oriented transport of photo‐induced carriers and achieved a high PCE over 21%.…”

Section: Introductionmentioning

confidence: 99%

Synergistic Reinforcement of Built‐In Electric Fields for Highly Efficient and Stable Perovskite Photovoltaics

Wang

Chen

Chiang

et al. 2020

Adv Funct Materials

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Perovskite solar cells (PSCs) have received great attention due to their outstanding performance and their low processing costs. To boost their performance, one approach is to reinforce the built-in electric field (BEF) to promote oriented carrier transport. The BEF is maximized by reinforcing the work function difference between cathode and anode (Δμ 1 ) and increasing the work function difference between lower and upper surfaces of perovskite film (Δμ 2 ) via introduction of electric dipole molecules, denoted as PTFCN and CF3BACl. The synergistic reinforcement of BEF improves charge transport and collection, and realizes markedly high photovoltaic performances with the best power conversion efficiency (PCE) up to 21.5%, a growth of 15.6% as compared to the control device, which is higher than the superposition of improvements achieved by either raising Δμ 1 or Δμ 2 . Importantly, dual-functional CF3BACl not only supplies dipole effect for tuning the surface potential of perovskite but offers hydrophobic trifluoride group toward the long-term stable unencapsulated PSCs retaining more than 95% PCE after storing 2000 h under ambient conditions. This work demonstrates the synergistic effect of Δμ 1 and Δμ 2 , providing an effective strategy for the further development of PSC in terms of photovoltaic conversion and stability.

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Introducing paired electric dipole layers for efficient and reproducible perovskite solar cells

Abstract: The paired electric dipole layers significantly intensify the built-in field across the perovskite layer, resulting in suppressed charge trapping of photogenerated charges.

Cited by 76 publications

References 55 publications

Efficient All‐Solution‐Processed Perovskite Light‐Emitting Diodes Enabled by Small‐Molecule Doped Electron Injection Layers

Efficient All‐Solution‐Processed Perovskite Light‐Emitting Diodes Enabled by Small‐Molecule Doped Electron Injection Layers

Conjugated Molecules “Bridge”: Functional Ligand toward Highly Efficient and Long‐Term Stable Perovskite Solar Cell

Synergistic Reinforcement of Built‐In Electric Fields for Highly Efficient and Stable Perovskite Photovoltaics

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