The power conversion efficiency of perovskite solar cells (PSCs) has ascended from 3.8% to 22.1% in recent years. ZnO has been well‐documented as an excellent electron‐transport material. However, ...the poor chemical compatibility between ZnO and organo‐metal halide perovskite makes it highly challenging to obtain highly efficient and stable PSCs using ZnO as the electron‐transport layer. It is demonstrated in this work that the surface passivation of ZnO by a thin layer of MgO and protonated ethanolamine (EA) readily makes ZnO as a very promising electron‐transporting material for creating hysteresis‐free, efficient, and stable PSCs. Systematic studies in this work reveal several important roles of the modification: (i) MgO inhibits the interfacial charge recombination, and thus enhances cell performance and stability; (ii) the protonated EA promotes the effective electron transport from perovskite to ZnO, further fully eliminating PSCs hysteresis; (iii) the modification makes ZnO compatible with perovskite, nicely resolving the instability of ZnO/perovskite interface. With all these findings, PSCs with the best efficiency up to 21.1% and no hysteresis are successfully fabricated. PSCs stable in air for more than 300 h are achieved when graphene is used to further encapsulate the cells.
Surface passivation of ZnO by a thin layer of MgO and protonated ethanolamine readily makes ZnO a very promising electron‐transporting material for creating efficient, hysteresis‐free and stable perovskite solar cells (PSCs). PSCs, stable in air for more than 300 h, are achieved when graphene is used to encapsulate the cells.
An electron‐transport layer (ETL) with appropriate energy alignment and enhanced charge transfer is critical for perovskite solar cells (PSCs). However, interfacial energy level mismatch limits the ...electrical performance of PSCs, particularly the open‐circuit voltage (VOC). Herein, a simple low‐temperature‐processed In2O3/SnO2 bilayer ETL is developed and used for fabricating a new PSC device. The presence of In2O3 results in uniform, compact, and low‐trap‐density perovskite films. Moreover, the conduction band of In2O3 is shallower than that of Sn‐doped In2O3 (ITO), enhancing the charge transfer from perovskite to ETL, thus minimizing VOC loss at the perovskite and ETL interface. A planar PSC with a power conversion efficiency of 23.24% (certified efficiency of 22.54%) is obtained. A high VOC of 1.17 V is achieved with the potential loss at only 0.36 V. In contrast, devices based on single SnO2 layers achieve 21.42% efficiency with a VOC of 1.13 V. In addition, the new device maintains 97.5% initial efficiency after 80 d in N2 without encapsulation and retains 91% of its initial efficiency after 180 h under 1 sun continuous illumination. The results demonstrate and pave the way for the development of efficient photovoltaic devices.
A simple low‐temperature‐processed In2O3/SnO2 bilayer electron‐transport layer (ETL) is used for fabricating efficient perovskite solar cells (PSCs). The bilayer ETL with appropriate energy alignment is beneficial for charge transfer, thus minimizing open‐circuit voltage (VOC) loss. An optimized planar PSC with a power conversion efficiency (PCE) of 23.24% is obtained. In contrast, devices based on single SnO2 only achieve efficiency of 21.42%.
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•FPBA passivate SnO2 defects, reduce non-radiative recombination at ETL/perovskite.•FPBA improve the surface energy of SnO2, which is beneficial to perovskite growth.•Carrier ...separation and transportation are improved due to the formation of dipoles.•The PCE of the Pero-SC was improved from 20.38% to 22.36% upon FPBA modification.•The Pero-SCs with FPBA kept 82% of the initial PCE over 3000 h storage in N2.
SnO2 has recently emerged as a promising Electron transportation layer (ETL) for perovskite solar cells (Pero-SCs). However, its inherent trap-states usually cause charge recombination, and its conductive band does not match well with that of the perovskite film. In order to solve these problems, we herein employed 3,5-Difluorophenylboronic acid (denoted by FPBA) to modify SnO2. After modification, the trap state density of SnO2 is drastically reduced, and better energy-level alignment is formed with perovskite owing to the interfacial dipole of FPBA. Consequently, the champion Power conversion efficiency (PCE) of Pero-SCs is increased from 20.38% to 22.36% after SnO2 being modified with FPBA. Moreover, the unencapsulated device based on FPBA-modified SnO2 maintains 82% of the initial PCE after being stored in nitrogen atmosphere for more than 3000 h.
Recent perovskite solar cell (PSC) advances have pursued strategies for reducing interfacial energetic mismatches to mitigate energy losses, as well as to minimize interfacial and bulk defects and ...ion vacancies to maximize charge transfer. Here nonconjugated multi‐zwitterionic small‐molecule electrolytes (NSEs) are introduced, which act not only as charge‐extracting layers for barrier‐free charge collection at planar triple cation PSC cathodes but also passivate charged defects at the perovskite bulk/interface via a spontaneous bottom‐up passivation effect. Implementing these synergistic properties affords NSE‐based planar PSCs that deliver a remarkable power conversion efficiency of 21.18% with a maximum VOC = 1.19 V, in combination with suppressed hysteresis and enhanced environmental, thermal, and light‐soaking stability. Thus, this work demonstrates that the bottom‐up, simultaneous interfacial and bulk trap passivation using NSE modifiers is a promising strategy to overcome outstanding issues impeding further PSC advances.
Nonconjugated multi‐zwitterionic small‐molecule electrolyte (NSE) molecules in perovskite solar cells (PSCs) act not only as both charge‐extracting layers for barrier‐free cathode charge collection but also as charged defect fillers in perovskite bulk and interfaces by spontaneous bottom‐up passivation. Thus, the NSE‐based PSCs deliver PCEs as high as 21.18% with an ultrahigh VOC of 1.19 V, suppressed hysteresis, and enhanced stability.
SnO2 Nanoparticles
In article number 2307958, Maria Antonietta Loi and co‐workers show that washing of the surface ions from the SnO2 layer improves the interface properties of organic solar cells.
The electron transport layer is one of the key factors in constructing high-performance perovskite solar cells (PSCs). Pb2+ reduction induced by ultraviolet light can cause the generation of ...vacancies and defects, leading to the degradation of perovskite films and the reduction of PSCs performances. Ethylenediamine tetraacetic acid disodium salt (EDTA) is a chelating agent that can bind to Sn2+ divalent metal ions and hence change material properties. Herein, EDTA-SnO2/CeO2 composite electron transport layers were constructed to improve the ultraviolet light stability of PSCs. The oxygen defect in electron layers of tin dioxide could be passivated by the surface of EDTA; whilst rod-like CeO2 was used as a mesoporous electron transport layer and UV shielding agent, which can reflect UV light and prevent the absorption layer from being damaged. CeO2 has also a suitable band gap; this accelerates the charge extraction and transfer, suppresses the recombination of interfacial carriers. The experimental results showed that the ultraviolet light stability of PSCs was significantly improved. After continuous irradiation of ultraviolet light with energy of 80 mW/cm2 for 12 h, the unencapsulated device with CeO2 maintained nearly 90% the initial efficiency.
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The fascinating structural, optical, and electronic features of calcium nitrogen iodide (Ca3NI3) make it an attractive material for developing absorbers for efficient and reasonably priced ...applications involving solar cells. Potential applications as an absorber layer in heterostructure solar cells for the perovskite material Ca3NI3 have been thoroughly studied theoretically. For the Ca3NI3 absorber-based cell structure with CdS as the ETL layer, the best PV values were discovered using the SCAPS-1D simulator. Working temperatures, interface densities of active materials, doping densities, and layer thicknesses were all carefully considered while analyzing the PV performance. It was also possible to find the quantum efficiency (QE), generation and recombination rates, and current density-voltage (J-V). The structure composed of Al/FTO/CdS/Ca3NI3/Ni demonstrated a remarkable power conversion efficiency (PCE) of 31.31%. With CdS serving as the electron transport layer (ETL), the high efficiency was matched by a current density (JSC) of 43.590813 mA/cm2, a fill factor (FF) of 81.68%, and an open-circuit voltage (VOC) of 0.8793 V. This work contributes to a better understanding of the potential of Ca3NI3 in heterostructure perovskite solar cells, which will facilitate the creation of more robust and efficient PSC devices.
•The way this perovskite solar cell is combined is unique.•The structure's inadequate thickness will result in lower costs.•The potential of the Ca3NI3 absorber has been systematically investigated and evaluated utilizing CdS electron transport layers (ETLs) at various layer thicknesses, defect densities, and doping levels.•The greatest power conversion efficiency for the Al/FTO/CdS/Ca3NI3/Ni structure was determined to be 31.31%, with a current density (JSC) of 43.590813 mA/cm2, a fill factor (FF) of 81.68%, and an open-circuit voltage (VOC) of 0.8793 V.•The evaluation of modern solar cells will be greatly aided by this structure.
Perovskite solar cells (PSCs) are promising to reduce the cost of photovoltaic system due to their low‐cost raw materials and high‐throughput solution process; however, fabrication of all the active ...layers in perovskite modules using a scalable solution process has not yet been demonstrated. Herein, the fabrication of highly efficient PSCs and modules in ambient conditions is reported, with all layers bladed except the metal electrode, by blading a 36 ± 9 nm‐thick electron‐transport layer (ETL) on perovskite films with a roughness of ≈80 nm. A combination of additives in phenyl‐C61‐butyric acid methyl ester (PCBM) allows the PCBM to conformally cover the perovskites and still have a good electrical conductivity. Amine‐functionalized molecules are added to enhance both the dispersity of PCBM and the affinity to perovskites. A PCBM dopant of 4‐(2,3‐dihydro‐1,3‐dimethyl‐1H‐benzimidazol‐2‐yl)‐N,N‐dimethylbenzenamine (N‐DMBI) recovers the conductivity loss induced by the small amine molecules. PSCs (0.08 cm2) fabricated by the all‐blading process reache an average efficiency of 22.4 ± 0.5% and a champion efficiency of 23.1% for perovskites with a bandgap of 1.51 eV, with much better stability compared to evaporated ETL PSCs. The all‐bladed minimodule (25.03 cm2) shows an aperture efficiency of ≈19.3%, showing the good uniformity of the bladed ETLs.
All the reported perovskite modules have a combination of different deposition methods for the perovskites and the charge‐transport layers, which limits high‐throughput module production. A combination of any amine molecules and 4‐(2,3‐dihydro‐1,3‐dimethyl‐1H‐benzimidazol‐2‐yl)‐N,N‐dimethylbenzenamine (N‐DMBI) added in phenyl‐C61‐butyric acid methyl ester (PCBM) allows the electrically conductive PCBM layers to conformally cover the perovskites and achieve high‐efficiency PSCs and modules with all‐bladed perovskite and charge‐transport layers.
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•A novel ZnO/Ti3C2Tx composite electron transport layer was fabricated.•ZnO/Ti3C2Tx ETL presents high efficiency and excellent stability.•Ti3C2Tx constructs additional charge transfer ...paths in composite ETL.•Ti3C2Tx passivates the surface of ZnO by forming Zn-O-Ti bonding.
MXenes, a novel intriguing family of two-dimensional (2D) transition metal carbides and nitrides, have a wide spectrum of applications owning to their unique optical and electronic properties. Herein, we use Ti3C2Tx, a representative of MXenes, as an additive in zinc oxide (ZnO) to fabricate novel ZnO/Ti3C2Tx nanohybrid composite film. The addition of Ti3C2TX nanosheets constructs new electron transport pathways between the ZnO nanocrystals, and passivates the surface of ZnO by forming the Zn-O-Ti bonding on the ZnO surface. The novel ZnO/Ti3C2Tx nanohybrid film exhibits excellent photoelectric characteristics, and is used as electron transport layers (ETLs) in fullerene and non-fullerene polymer solar cells for the first time. As a result, the power conversion efficiency (PCE) of the photovoltaic devices based on PBDB-T:ITIC with the ZnO/Ti3C2Tx ETLs is 12.20%, up from 10.56% for the corresponding device utilizing pristine ZnO as ETL, a relative increase of 15.53%. Moreover, PM6:Y6 based IPSCs achieve a champion PCE of 16.51% from 14.99% for the reference device, suggesting the good applicability of the ZnO/Ti3C2Tx ETL. The enhancement of PCE is mainly due to the increased transfer and collection of charges in IPSCs. More interestingly, devices based on ZnO/Ti3C2TX composite ETL display relatively good stability compared with the control device. The layered Ti3C2TX should be responsible for such enhancement.
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