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The numerous defect‐induced non‐radiative recombination losses and residual stress in the preparation of perovskite film greatly hinder the further improvement of the efficiency and stability of flexible perovskite solar cells (PSCs). Here, a natural spice 7‐amino‐4‐(trifluoromethyl)‐2‐benzopyrone (ATB) containing amino (─NH2), carbonyl (─C═O), and trifluoromethyl (─CF3) functional groups is introduced into the perovskite precursor solution, thereby preparing high‐quality perovskite film with low defect density. It is revealed that the utilization of ATB is beneficial to comprehensively passivate the defects and release the residual stress of perovskite film through the synergistic effect of functional groups, thereby improving the crystallinity and enhancing the carrier lifetime of perovskite film. Moreover, the introduction of ATB contributes to an improved energy levels alignment between the perovskite and adjacent layers, which facilitates fast carrier transport and suppresses the recombination loss in the flexible PSCs. Combined with the multifunctional effects of ATB, the target flexible and rigid PSCs with ATB modification yield remarkable photoelectric conversion efficiency (PCE) of 21.08% and 23.79%, respectively. More importantly, the ATB‐modified flexible device exhibits outstanding stability and retains 87.3% and 91.6% of the original efficiency after aging for 3000 h at 50 ± 5 relative humidity and 5000 bending cycles, respectively. [ABSTRACT FROM AUTHOR]

In this study, ZnO/Zn 2 SnO 4 (ZSO) composite is synthesized as a promising alternative compact layer to TiO 2 by spray pyrolysis method. Owing to the ZnO/ZSO composite possesses higher carrier mobility and suitable band gap structure, it will behave well in the application of solar cells. The characterization results show that the ZnO/ZSO composite compact layer manifests better optical transmittance, enhanced electrons collective efficiency and superior electrical conductivity. Consequently, the corresponding photo-current is improved effectively when compared with that of TiO 2 compact layer. The optimum efficiency of perovskite solar cell based on the ZnO/ZSO composite compact layer reaches 12.03% at AM 1.5 solar light of 100 mW cm −2 , which is 18% higher than that of perovskite solar cell based on the TiO 2 compact layer. [ABSTRACT FROM AUTHOR]

In this paper, high efficient and stable planar perovskite solar cells (PKSCs) have been designed and fabricated via employing high transparent Mg-doped ZnO films with excellent electron transport ability as a novel class of electron transport layers (ETLs). Due to the optimized band alignment by Mg doping, the photogenerated electron injection and charge extraction from the perovskite film to ETL have been facilitated effectively and the planar PKSC based on 2% Mg-doped ZnO and MAPbI 3 yields the maximum power conversion efficiency (PCE) of up to 16.74%. Meanwhile, a higher PCE of 17.85% through a phenyl C 60 butyric acid methyl ester (PCBM) interfacial layer between the 2% Mg-doped ZnO and perovksite layer has been achieved for the first time. Moreover, the PKSCs with 2% Mg-doped ZnO/PCBM composite ETLs also demonstrate outstanding long term device stability and up to 91% of original PCE of the PKSCs, which can be retained even after exposure in ambient conditions over three-months. [ABSTRACT FROM AUTHOR]

By dipping the mesoporous TiO 2 film in Sr 2+ solutions and subsequent annealing, a modification layer of SrTiO 3 has been formed on the surface of the mesoporous TiO 2 film, and the effect of modification on the photovoltaic characteristics of the perovskite solar cells has been studied detailedly. The XPS and TEM results verified the existence and nature of the SrTiO 3 modification layer. Benifiting from the TiO 2 surface modification, the morphology of perovskite film and light absorption of the CH 3 NH 3 PbI 3 absorber have been improved effectively, and a faster charge transfer has also been achieved between the CH 3 NH 3 PbI 3 perovskite layer and the modified TiO 2 . As a result, an average conversion efficiency of 11.4% has been achieved in the perovskite solar cell based on the modified mesoporous TiO 2 by 10 mM Sr 2+ solution, and it increases approximately by 46% in comparison with the photovoltaic efficiency of 7.8% of the perovskite solar cell based the bare mesoporous TiO 2 layer. [ABSTRACT FROM AUTHOR]

[Display omitted] The severe non-radiative recombination loss caused by SnO 2 /perovskite interface defects greatly hinders the further improvement of the performance and stability of flexible perovskite solar cells (PSCs). Herein, a series of halides KM (M = F, Cl, Br, I) were inserted as interface layers to modulate the SnO 2 /perovskite interface. Both experimental and theoretical calculation demonstrated that F− exhibited stronger interface coupling effect between the SnO 2 and perovskite than other halide ions (Cl−, Br−, I−). The F− had unique effects in effectively depressing SnO 2 /perovskite interface defects ascribed to the simultaneous formation of Sn F bonds and hydrogen bonds, resulting in reduced non-radiative recombination and improved interfacial contact. In consequence, the champion KF-modified flexible and rigid PSCs delivered outstanding PCE of 18.16 % and 21.36 %, accompanied by the enhanced V OC of 1.14 V and 1.16 V, respectively. Meanwhile, the stability of flexible PSCs was significantly ameliorated after KF modification, and about 84 % of the original efficiency could be retained even after 3000 bending cycles. This work provides a facile and efficient strategy for interface modulation to achieve high-performance and stable flexible PSCs. [ABSTRACT FROM AUTHOR]

In this study, high coverage and uniformly distributed Bi 2 S 3 and Sb 2 S 3 quantum dots (QDs) are deposited simultaneously on the surface of TiO 2 nanorods (NRs) via electrochemical atomic layer deposition (ECALD) method. The structure, morphology and composition of the deposits are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersion spectroscopy analysis (EDS), respectively. The results show that the deposits are of Bi 2 S 3 and Sb 2 S 3 compound semiconductor, and the Bi 2 S 3 /Sb 2 S 3 QDs cover on the top and side surface of TiO 2 NRs homogeneously. EDS analysis demonstrates that the ratio of both S to Sb and S to Bi are approximately 3:2, indicating that ECALD method can well control the deposition of each element. Owing to the better light absorption property and reduced recombination possibility of Bi 2 S 3 /Sb 2 S 3 QDs co-sensitized solar cells, the power conversion efficiency reaches 0.67% with a short-circuit current density of 4.83 mA cm −2 at AM 1.5 solar light of 100 mW cm −2 , which is much higher than that of Bi 2 S 3 or Sb 2 S 3 QDs sensitized solar cells. [ABSTRACT FROM AUTHOR]

A novel bi-layer structure assembled by nanorods and three-dimensional hierarchical TiO 2 is synthesized by a facile two step hydrothermal method. By adjusting the acid concentration, the morphology of three-dimensional hierarchical TiO 2 can be well controlled. This bi-layer structure combines the merits of one-dimensional nanorods which can serve as direct electrons transport pathways and three-dimensional hierarchical structure supplying light scattering ability and large specific surface area for dye loading. Hence, the photovoltaic performance of the dye-sensitized solar cells based on the bi-layer TiO 2 is greatly enhanced compared to that of single nanorods film. The maximum short-circuit current and power conversion efficiency of the DSSCs based on bi-layer TiO 2 structure reach 12.55 mA/cm 2 and 5.61% respectively, which are remarkably larger than those of 5.00 mA/cm 2 and 2.38% for the DSSC based on a single layer TiO 2 nanorods film. The superior performance of bi-layer TiO 2 structure is attributed to the large dye loading amount and light scattering properties due to the unique hierarchical structure. [ABSTRACT FROM AUTHOR]

Abstract Here, we demonstrate a facile strategy to enhance the efficiency and stability of perovskite solar cells (PKSCs) by modification the perovskite with a simple small molecule SnPc layer. A maximum PCE of 16.52% has been achieved in the modified PKSCs and it increases by 25% in compared with the pristine device (13.2%). The improvement of photovoltaic performance should be ascribed to the enhancement of holes transport and the reduction of charge recombination by SnPc modification. Moreover, the stability of PKSCs has also been improved remarkably due to the protection of the hydrophobic SnPc layer, and the device can keep over 86% initial PCE even after exposure for 90 days under ambient environment (25 °C relative humidity RH = 30%) without encapsulation. [ABSTRACT FROM AUTHOR]

• An efficient dual-interface engineering is employed in flexible device. • The flexible and rigid PSCs achieve PCE of 20.06% and 23.11%, respectively. • The flexible PSCs presents excellent bending durability after 5000 cycles. Defect-induced charge non-radiative recombination loss at perovskite/charge transport layers (CTLs) interfaces greatly deteriorates the efficiency and stability of flexible perovskite solar cells (PSCs). Therefore, a comprehensive strategy for reducing the defect density both at perovskite/CTLs interfaces is urgently required. Herein, the 1-[3-(Trimethoxysilyl)propyl]urea (TMPU) material is adopted to improve the conductivity of SnO 2 and passivate the unfavorable SnO 2 /perovskite interface defects. Meanwhile, the trimethoxy(3,3,3-trifluoropropyl)silane (TMFS) layer is employed at perovskite/spiro-OMeTAD interface for the sake of suppressing the surface defects of perovskite and ameliorating environmental stability of the perovskite. Such a dual-interface engineering strategy is beneficial to significantly reduce interface defect density and unfavorable non-radiative recombination loss, thus achieving faster transport and effective collection of carriers. Consequently, the optimized flexible and rigid PSCs yield outstanding photoelectric conversion efficiency (PCE) of 20.06% and 23.11%, respectively, which are both significantly higher than the pristine devices. Notably, the target flexible device presents excellent mechanical durability and retains 91.3% of the initial PCE after 5000 bending cycles with bending radius of 10 mm. [ABSTRACT FROM AUTHOR]

[Display omitted] • Vacancy compensation and defect passivation are achieved by Na 2 S treatment. • The formed Pb-S-Sn conductive channel accelerates charge transport. • Increased built-in electric field suppresses carrier recombination. • The optimized PSCs exhibit reduced hysteresis and enhanced stability. Interfacial defects at the electron transport layer (ETL) and perovskite interface significantly impact the interface carrier dynamics and thus the performance of planar perovskite solar cells. Here, a synergistic strategy has been proposed to compensate for oxygen vacancies and halogen vacancies at the ETL/perovskite interface by constructing a Na 2 S interface layer. The results show that the S atoms simultaneously bond with the Sn atoms in SnO 2 and occupy the halogen vacancies in the perovskite and form a Pb-S-Sn conductive channel, which accelerates carrier extraction at the interface. In addition, the Na 2 S interface layer affects the growth of the perovskite film and passivates the grain boundaries, resulting in reduced defect density and increased grain size. Correspondingly, the target device achieves a significantly improved efficiency (21.2 %) compared to the pristine device (17.2 %) and maintains over 86 % of the initial efficiency after aging in the air for 1000 h with 35 % RH; while exhibiting improved humidity and thermal stability. The interface defect compensation strategy reported herein provides a simple and effective method for interface optimization to further improve device performance. [ABSTRACT FROM AUTHOR]

The ETL/perovskite interface is crucial for the photovoltaic performance of perovskite solar cells (PSCs) because of its key role in electrons transport and charge recombination. Herein, an ultrathin CaTiO 3 layer has facilely been fabricated and incorporated between the mp-TiO 2 and perovskite layers. Due to the trap passivation effect and the optimized energy level alignment induced by modification, the electron transport is facilitated while the charge recombination is suppressed effectively. Therefore, the champion device gains a maximum PCE of 19.12% with the enhanced photovoltaic performance. In addition, the stability of PSCs has also been ameliorated by modification, and about 85% of the initial efficiency can be maintained even after exposure in ambient for 1000h. Image 1 • Ultrathin CaTiO 3 layer modified mp-TiO 2 was achieved by spin coating. • Modification induced trap passivation effect and optimized energy level alignment. • Electron transport is facilitated with effectively suppressed charge recombination. • Photovoltaic performance and device stability has been enhanced remarkably. [ABSTRACT FROM AUTHOR]