Planar Heterojunction Perovskite Solar Cells Research Articles

Universal Strategy with Structural and Chemical Crosslinking Interface for Efficient and Stable Perovskite Solar Cells

AbstractDue to the limited interface contact and weak interfacial interaction, planar heterojunction perovskite solar cells (PSCs) have space for further improvement. Herein, a structural and chemical crosslinking interface is proposed and constructed by introducing an extra layer, which blends tin dioxide (SnO2) nanoparticles with chloride salts. Since the incorporated materials can be dissolved during the fabrication of perovskite, the quality of perovskite films is improved, leading to larger grain size and reduced trap‐state density. Also, more chloride ions at the SnO2/perovskite interface are observed and the interaction between Cl− and Sn4+ is confirmed. It results in more pronounced n‐type SnO2 with better conductivity and deeper conduction bands, leading to preferable energy level alignment between SnO2 and perovskite. Consequently, the open‐circuit voltage and fill factor of the devices increase, and target cells present better stability, retaining 98% of initial efficiencies after >10 000 h storage in dry air (≈5% relative humidity) and maintaining 85.50% of the initial efficiency after 1000 h of operation under light. This strategy enables the achievement of 25.28% efficiency with a low bandgap (1.53 eV) perovskite composition, and it is confirmed to be universal when other related materials are utilized.

Review on Surface Modification of SnO2 Electron Transport Layer for High-Efficiency Perovskite Solar Cells

In the planar heterojunction perovskite solar cell (PSC) structure, among numerous contenders, tin oxide (SnO2) has been utilized, instead of TiO2, as the material for the electron transport layer (ETL) owing to its good band alignment, ultraviolet light resistance, strong charge extraction, and low photocatalytic activity. However, the morphology of the SnO2 ETL has proven to be unstable under low-temperature processing, leading to low electron extraction in PSCs. Therefore, the surface morphology must be modified to achieve high-performance PSCs. In this review, we provide an overview of the fundamental insights into how surface variations affect the ETL performance. The significance and the design rule of surface modification for an efficient SnO2 ETL, that is, the intentional alteration of the SnO2 interface, are discussed. Based on the evaluations, distinct surface engineering procedures and how they are implemented are presented. The effects of chemical and physical interactions on the properties of SnO2 are elucidated in detail; these have not been considered in previous studies. Finally, we provide an outlook on, highlight the key challenges in, and recommend future research directions for the design of the interfaces of highly efficient and stable PSCs.

Pathway to the Polyvinyl‐Acetate‐Assisted PEDOT:PSS as a Dopant‐Free Hole Transporting Material in Planar Heterojunction Perovskite Solar Cells

To achieve world's burgeoning appetite in obtaining high‐energy conversion efficiency, not only perovskite semiconductor but also hole transporting material (HTM) takes a significant role as a game changer. The dopant of conventional organic HTM induces side effects of degradation, and inorganic HTM reacts or penetrates with the underlying perovskite layer. Considering those issues, poly(3,4‐ethylenedioxythiophene:poly(styrene sulfonate) (PEDOT:PSS) as an alternative HTM has been explored in the field of perovskite solar cells with its outstanding hole transporting property. Herein, incorporation of polyvinyl acetate (PVAc) in PEDOT:PSS paves the way to wide applications in device structural perspective, as to say, in n–i–p structure. The presence of the ester group in PVAc donates the bonding site to the perovskite layer, which improves the adhesion, resulting in enhanced charge transport ability as well as device stability. PVAc‐treated PEDOT:PSS device exhibited 20% higher power conversion efficiency (PCE) than the PVAc‐free device and retained 80% of initial PCE after 1000 h under extreme conditions (AM 1.5G and 60 °C).

P-n Homojunction perovskite solar cells: effects of ionic density and thickness of the doped layers

The p-n homojunction perovskite solar cells are promising in comparison to planar heterojunction perovskite solar cells. It is observed that the p-n homojunction provides an efficient built-in electric field for the photo-generated electron-hole pairs to dissociate into free charge-carriers and orient them to transport to the respective electrodes, thereby reducing the overall losses due to recombination processes. However, the existence of p-n homojunction, while in operation, is currently undergoing experimental tests. In this study, we simulated the current-voltage characteristics of both planar heterojunction and p-n homojunction perovskite solar cells. For simulation, we utilised a one-dimensional drift-diffusion equation. The current-voltage characteristics show a high fill factor for the p-n homojunction devices indicating better power conversion efficiency as compared to that of planar heterojunction devices. In addition, we report the spatial distribution of electron- and hole-density with variations in (i) the mobile ionic density, inherently present in the perovskite material and (ii) the thickness of p- and n-type perovskite layers. It is observed that the role of p-n homojunction ceases when the ionic density is higher than 1017 cm−3 or when one of the doped layers is substantially thicker as compared to the other. We correlate the cease of p-n homojunction to (i) the ionic effect which screens the built-in field, and (ii) the predominance of the effect of one doped layer over the other. The study provides impetus to the development of the p-n homojunction perovskite solar cells.

Electron transport layer of tin dioxide deposited by reactive plasma and its application in perovskite solar cells

The electron transport layer is very important for the device efficiency and stability of perovskite solar cells. Tin dioxide is a common electron transport layer in high-efficiency solar cells and has good carrier extraction and transport capability. However, using the solution method to prepare tin dioxide, a large number of defects are generated on its surface during high-temperature annealing in air, which can degrade the electrical properties of the film, so the solution method is not conducive to preparing large-area film. In this paper, the reactive plasma deposition method is used to prepare tin dioxide thin film, and the performance of the thin film is optimized by adjusting the glow discharge time and working current. The film is applied to small-area N-I-P type perovskite solar cells, the efficiency reaching to 21.24%. The hysteresis of the device is improved by introducing stannous isooctanoate and tin dioxide as a double electron transport layer, the open circuit voltage of the solar cell increases from 1.11 to 1.15 V, the efficiency rises from 21.27% to 22.15%, and the hysteresis factor decreases from 24.04% to 3.69%. This work presents a new preparation method and effective optimization strategy to prepare tin dioxide electron transport layer, which will promote the development of planar heterojunction perovskite solar cells and provide a new research idea for preparing high-efficiency and stable perovskite solar cells.

Optimized perovskite active layer morphologies and crystallization by doping cesium iodide for high-performance bulk heterojunction solar cells and X-ray detectors

Organic-inorganic hybrid methylammonium lead iodide perovskite (MAPbI 3 ) has attracted widespread attention for its potential use in a range of optoelectronic devices. In this paper, we describe the fabrication of inverted-type perovskite/fullerene planar heterojunction perovskite solar cells and X-ray detectors where a small amount of cesium iodide (CsI) was added to the MAPbI 3 precursor solution. The appearance and crystal structure of the constructed perovskite active layer were carefully studied by microscope and X-ray diffraction measurements, respectively. The results reveal that the CsI additive can control the size and aggregation behavior of the perovskite crystals, helping to form a smoother perovskite film. Thus, the constructed perovskite solar cell with its Cs 0.1 MA 0.9 PbI 3 active layer (AC) revealed a power conversion efficiency (PCE) of 11.16 ± 0.13%, which is a significant improvement over conventional planar heterojunction devices that use pristine MAPbI 3 AC (PCE 9.12 ± 0.11%). We also fabricated an X-ray detector using the same Cs 0.1 MA 0.9 PbI 3 , this achieved a maximum sensitivity of 3.26 mA/Gy cm 2 . Density functional theory calculations investigate the origin of the enhancement of device performance characteristics. Interestingly, the results show that perovskite surfaces constructed with a suitable amount of CsI can effectively enhance charge extraction and reduce charge carrier recombination. This work provides an efficient way to improve carrier transfer, which will inspire other perovskites optoelectronic applications. • We have synthesized smooth and highly crystalline perovskite thin films by incorporating an appropriate amount of CsI. • We fabricated inverted-type perovskite/PCBM hybrid solar cells and X-ray detectors using cesium-doped perovskites. • Competitive efficiency of 11.16 ± 0.13% was achieved for constructed perovskite solar cell with Cs 0.1 MA 0.9 PbI 3 AC. • Invented X-ray detector with Cs 0.1 MA 0.9 PbI 3 AC exposed a high sensitivity of 3.26 mA/Gy·cm 2 .

2, 3, 4, 5, 6-Pentafluorophenylammonium bromide-based double-sided interface engineering for efficient planar heterojunction perovskite solar cells

In order to obtain high power conversion efficiency and high stability perovskite solar cells, many innovative optimization schemes have been proposed. Thereinto, the interface modification become an effective way to improve the performance of device. Here, A dual-interface passivation by 2, 3, 4, 5, 6-pentafluorophenylammonium bromide-based (5PFP-Br) is used to optimize the performance of device with the structure of ITO/SnO2/perovskite/PTAA/Ag. We design the 5PFP-Br layer at SnO2/perovskite and perovskite/PTAA interface respectively. The results show that the interface contact between perovskite and charge transport layer is improved obviously. At the same time, the density of carrier transport defect states in the device is reduced, thus reducing the non-radiative recombination of carriers. Meanwhile, the 5PFP-Br layer at perovskite/PTAA interface can effectively passivate Pb defects and reduce the number of grain boundaries in perovskite film, and increase the carrier transfer and collection efficiency. Finally, 5PFP-Br double-interface passivation can further optimize and improve the performance of device. The device based 5PFP-Br double-interface passivation presents an increased efficiency from 18.09% to 21.15%, where FF is raised from 73.30% to 80.04%. At the same time, unpackaged device can still be maintained to more than 90% efficiency after about 1200 h at 25 °C and 25%RH.

Doping Mechanism of Perovskite Films with PbCl2 Prepared by Magnetron Sputtering for Enhanced Efficiency of Solar Cells.

The last decade has witnessed a rapid growth of perovskite solar cells extended from mesoporous to planar architecture as well as from solution processing to solvent-free fabrication. The preparation of perovskite films by solvent-free method still presents significant challenges, such as the difficulty of film preparation by multiple evaporation sources in vapor deposition and the immaturity of the sputtered method. Here, we present a planar perovskite solar cell fabricated by solvent-free magnetron sputtering without the assistance of the mesoporous TiO2 layer, and lead chloride (PbCl2) was mechanically milled into the target of methylammonium lead halides (MAPbI3) to improve the quality of perovskite film by regulating the crystallization process with the Cl element. Furthermore, the internal reason for the effect of different PbCl2 doping contents on the trap density of perovskite films was also investigated in detail. These lead to an improved power conversion efficiency of planar heterojunction perovskite solar cells up to 17.10%, which is the highest efficiency recorded for the sputtered perovskite solar cells so far. The stability of resulting solar cells has also been significantly improved by exploring the doping mechanism of perovskite films with PbCl2 in detail, showing great research and application prospect.

Planar heterojunction perovskite solar cell with graded energy band architecture via fast-drying spray deposition

The fast-drying spray deposition (FDSD) technique for perovskite solar cells (PSCs) is developed to enable the stacking of perovskite absorbers with different work functions, which allows the creation of an additional built-in electric field at the interface during the fermi level realignment process upon contact. FDSD is functional under high relative humidity (RH) ambiance and by design, deposits dry film without the need for post-deposition annealing treatment. Based on a spray coating process, FDSD is also highly scalable. Leveraging FDSD’s multilayer deposition capability, this work explores the implementation of graded energy band architectures to achieve PSCs with enhanced carrier extraction and photovoltaic performances. To demonstrate the potential benefit of this approach, two triple cation mixed halide perovskite formulas are chosen. The two formulas, when stacked together in correct order, produce a heterojunction PSC device with an extra built-in electric field, which helps drift charge carriers towards desired electrodes. The architecture with the proper energy band alignment therefore exhibits enhanced carrier extraction efficiency and, despite being subjected to over 60–80% RH during fabrication, reaches the mean power conversion efficiency (PCE) of 7.4%, with the maximum value of 9.5%. The average PCE translates to over 9.9% and 10.3% improvements over the devices based on the two constituent formulas individually. FDSD demonstrates great flexibility i.e., in-humid-air fabrication process and requiring no post annealing treatments, thereby enabling extremely robust and scalable stacked architecture PSCs with low cost and good performance.

An energy level alignment strategy to boost the open-circuit voltage via a Mg:TiO2 compact layer in the planar heterojunction CsPbBr3 solar cells

The suitable energy level alignment between the electron transport layer (ETL) and perovskite absorber for facilitating electron extraction and transfer is essential for planar heterojunction perovskite solar cells (PSCs) to achieve high power conversion efficiency (PCE). The planar heterojunction CsPbBr3 PSCs have attracted increasing attention due to their high stability in ambient in which TiO2 is often used as the ETL. Actually, there is a large energy barrier between the conduction bands of TiO2 and CsPbBr3, which limits the open-circuit voltage (VOC) and PCE of PSCs. Herein, we effectively optimized the energy level alignment between CsPbBr3 and TiO2 by tuning the Mg incorporation level in the latter. The Fermi level of TiO2 ETL was gradually shifted upward using Mg incorporation, which led to a favorable band bending between TiO2 and CsPbBr3 and reduced the interfacial band offset. Consequently, the VOC of the devices was effectively increased from 1.36 to 1.49 V, and the corresponding PCE was also increased from 6.87% to 8.76%. This work highlights the importance of the energy level alignment between ETLs and perovskite absorbers for high-performance devices and offers an effective means to address the large energy barrier between the conduction bands of TiO2 and CsPbBr3.

Current-voltage curves of planar heterojunction perovskite solar cells – Novel expressions based on Lambert W function and Special Trans Function Theory

IntroductionAt the present time, much attention has been focused on new types of solar cells, called perovskite solar cells. They are highly efficient devices with more than 25% power conversion efficiency. However, perovskite solar cell performance has not yet been fully explored. ObjectivesWe aimed to mathematically investigate the analytical modeling of current–voltage curves of planar heterojunction perovskite solar cells using Perovich Special Trans Function Theory (STFT). Furthermore, we proposed novel analytical closed-form solutions for short-circuit current and open-circuit voltage of these cells in terms of STFT. We evaluated the safety for laying the theoretical foundation by comparing the accuracy of the proposed expressions by the known methods. MethodsA novel hybrid metaheuristic algorithm, called particle swarm optimization (PSO) – evaporation rate water cycle algorithm (ERWCA), is proposed to determine equivalent circuit parameters of the perovskite solar cell. A novel objective function is introduced for estimating the parameters for that purpose too. ResultsIt was shown that STFT is very applicable and efficient for representing current–voltage expressions of perovskite solar cells. STFT provides a more accurate solution and requires fewer order members than the solutions provided by the conventional Taylor series. Based on these expressions and numerical calculations, it is verified that the characteristic values ​​of variables (short-circuit current, no-load voltage, efficiency, and fill factor) were not accurately calculated in the literature. Also, parameters of equivalent circuits of these cells were not accurately estimated. The equivalent circuit parameters were determined using the algorithm proposed in this work, which fit the verified values ​​of characteristic quantities much better than the literature. ConclusionThis work lays the foundation for developing the planar-structured perovskite solar cell models, in which the proposed estimation method and expressions are highly effective and provide excellent results.

Preparation of TiO[formula omitted] electron transport layer by magnetron sputtering and its effect on the properties of perovskite solar cells

Magnetron sputtering technology benefits from an easy process parameter adjustment strategy, good experimental reproducibility, and high-quality film formation; thus, it is widely used in thin-film electronic devices. In the present work, the thickness and morphology of the TiO2 electron transport layer were controlled by magnetron sputtering time, and based on this technology, planar heterojunction perovskite solar cells were prepared. The results showed that with an increase in the sputtering time, the surface roughness of the TiO2 film decreased, and the electrical homogeneity and square resistance of the film increased. Especially, the film transmittance showed a maximum value of 82.29% at 45 min of deposition, and the so prepared perovskite solar cells exhibited the highest photoelectric conversion efficiency of up to 12.42%.

Photoelectric balance of rear electrode in bifacial perovskite solar cells: Construction of 0D/1D/2D composite electrode based on silver nanowires to boost photovoltaic output

Photoelectric imbalance problems of rear transparent conductive electrodes (TCEs) limit the photovoltaic (PV) performance of bifacial planar heterojunction perovskite solar cells (PH–PSCs). We exploit the superior electrical advantages of 0-dimensional (0D) carbon quantum dots (C QDs), 1-dimensional (1D) silver nanowires (Ag NWs), and 2-dimensional (2D) ultrathin Ag films to develop a novel rear TCE with ideal photoelectric balance, i.e., Ag NW + C QD/Ag NW/molybdenum oxide (MoOx)/ultrathin Ag (denoted as A + C/A/M/A) rear TCE with a 0D/1D/2D composite structure. We show that C QDs fully fill the voids within the Ag NW network, which effectively accelerates the charge transfer/collection, thereby enhancing the PV output of PH-PSCs. Moreover, the film quality and photoelectric properties of the rear TCEs are further improved by depositing the MoOx/ultrathin Ag films onto the A + C composite network, which significantly improves PV performance. More importantly, MoOx is key to realizing the photoelectric balance of rear TCEs because it not only has excellent antireflection effects, but also promotes the formation of high-quality ultrathin Ag film. As a result, the efficiencies of the A + C/A/M/A-based PH-PSC under front and rear illuminations are 16.09% and 12.59%, respectively, which are superior to that of most reported Ag NW-based PSCs.

Combining in-situ formed PbI2 passivation and secondary passivation for highly efficient and stable planar heterojunction perovskite solar cells

Since the power conversion efficiencies of organic-inorganic hybrid perovskite solar cells have a rapid development due to their high light absorption coefficient, tunable band gap and low fabrication cost, they have received much attention. The thin film formation and properties have significant effects on the final device performance. While how to control the thin film evolution and introduce film passivation is a critical issue to improve the device efficiency. In this study, we studied the controlled in-situ PbI 2 formation during the thin film evolution, and its effect on thin film properties, as well as their passivation effects on the photovoltaic device performance. The final thin film properties are critically related with the precursor used and chlorine inclusion could change the final thin film compositions, and affect the solar cell performance. We further perform a secondary passivation by reacting the excess PbI 2 with large organic cation to form 2D perovskite. Based on in-situ PbI 2 passivation and secondary 2D perovskite passivation, the devices exhibit a higher PCE of 21.1% and excellent V oc of 1.14 V. • Controlled in-situ PbI2 formation during the film evolution is achieved. • 2D perovksites as secondary surface passivation by reacting the excess PbI2. • A higher PCE of 21.1% and excellent V oc of 1.14 V are achieved via controlled in-situ PbI2 and 2D perovksite passivation.

Low-temperature preparation of SnO<sub>2</sub> electron transport layer for perovskite solar cells

SnO<sub>2</sub> has the advantages of excellent photostability and can be prepared at low-temperature below 200 ℃. It is regarded as one of the excellent materials for the electron transport layer, and widely used in efficient and stable planar heterojunction perovskite solar cells. In this work, the low-cost, dense and uniform SnO<sub>2</sub> electron transport layer is prepared by spin coating at low temperature (150 ℃) for perovskite solar cells with a structure of FTO/SnO<sub>2</sub>/CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> (MAPbI<sub>3</sub>)/Spiro-OMeTAD/Au. The crystallization and photoelectric properties of SnO<sub>2</sub> electron transport layers prepared at different concentrations (2.5%–10%) at 150 ℃, and the influences of SnO<sub>2</sub> electron transport layers on the formation of perovskite films and the performances of perovskite solar cells are discussed. By analyzing the scanning electron microscope (SEM), ultraviolet-visible light absorption spectrum (UV-Vis) and transmission spectrum of the SnO<sub>2</sub> film, it is found that the coverage and light transmittance of the substrate and band gap of the SnO<sub>2</sub> film increase as the SnO<sub>2</sub> content increases, while the absorbance decreases. By analyzing the SEM, UV-Vis, X-ray diffraction (XRD) and steady-state photoluminescence spectrum (PL) analysis of the SnO<sub>2</sub>/MAPbI<sub>3</sub> thin film, it is found that the MAPbI<sub>3</sub> deposited on the SnO<sub>2</sub> layer with a concentration of 7.5% is uniform and pinhole-free, has the largest particle size and the best crystallinity, as well as more effective charge extraction capability and transport capability. By analyzing the electrochemical impedance (EIS) and external quantum efficiency (EQE) of the device, the SnO<sub>2</sub> electron transport layer with a concentration of 7.5% has better interface contact and lower interface resistance, which is beneficial to reducing the recombination of carriers and improving the photoelectric conversion capability, The perovskite solar cells based on SnO<sub>2</sub> layer prepared with a concentration of 7.5% reaches a photoelectric conversion efficiency of 15.82% (<i>V</i><sub>oc</sub> = 1.06 V, <i>J</i><sub>sc</sub> = 21.62 mA/cm<sup>2</sup>, FF = 69.40%), After storing for 600 h in ambient air ((25±5) ℃, RH>70%) without encapsulation, its efficiency remains 92% of the initial efficiency. At the same time, we prepare flexible devices on flexible substrates (TIO/PEN) by using SnO<sub>2</sub> precursor with a concentration of 7.5%, which exhibits good photovoltaic performance and achieves a photoelectric conversion efficiency of 13.12%, and storage time for 84 d in ambient air ((30±5) ℃, RH>70%) without encapsulation, its efficiency remains 48% of the initial efficiency. The PCE retains 78% of the initial efficiency after 1000 bending cycles with a bending radius of 3 mm. The study of optimizing the concentration of SnO<sub>2</sub> has laid a foundation for improving the performance of flexible perovskite solar cells.

Inverted Planar Heterojunction Perovskite Solar Cells with High Ultraviolet Stability

Inverted Planar Heterojunction Perovskite Solar Cells with High Ultraviolet Stability

Designing New Indene-Fullerene Derivatives as Electron-Transporting Materials for Flexible Perovskite Solar Cells.

The synthesis and characterization of a family of indene-C60 adducts obtained via Diels–Alder cycloaddition [4 + 2] are reported. The new C60 derivatives include indenes with a variety of functional groups. These adducts show lowest unoccupied molecular orbital energy levels to be at the right position to consider these compounds as electron-transporting materials for planar heterojunction perovskite solar cells. Selected derivatives were applied into inverted (p–i–n configuration) perovskite device architectures, fabricated on flexible polymer substrates, with large active areas (1 cm2). The highest power conversion efficiency, reaching 13.61%, was obtained for the 6′-acetamido-1′,4′-dihydro-naphtho[2′,3′:1,2][5,6]fullerene-C60 (NHAc-ICMA). Spectroscopic characterization was applied to visualize possible passivation effects of the perovskite’s surface induced by these adducts.

Preparation and characterization of planar heterojunction perovskite solar cells based on c-TiO2/CH3NH3PbI3/HTM/Ag structure

Preparation and characterization of planar heterojunction perovskite solar cells based on c-TiO2/CH3NH3PbI3/HTM/Ag structure

ZrSnO4: A Solution-Processed Robust Electron Transport Layer of Efficient Planar-Heterojunction Perovskite Solar Cells

A robust electron transport layer (ETL) is an essential component in planar-heterojunction perovskite solar cells (PSCs). Herein, a sol-gel-driven ZrSnO4 thin film is synthesized and its optoelectronic properties are systematically investigated. The optimized processing conditions for sol-gel synthesis produce a ZrSnO4 thin film that exhibits high optical transmittance in the UV-Vis-NIR range, a suitable conduction band maximum, and good electrical conductivity, revealing its potential for application in the ETL of planar-heterojunction PSCs. Consequently, the ZrSnO4 ETL-based devices deliver promising power conversion efficiency (PCE) up to 19.05% from CH3NH3PbI3-based planar-heterojunction devices. Furthermore, the optimal ZrSnO4 ETL also contributes to decent long-term stability of the non-encapsulated device for 360 h in an ambient atmosphere (T~25 °C, RH~55%,), suggesting great potential of the sol-gel-driven ZrSnO4 thin film for a robust solution-processed ETL material in high-performance PSCs.

High-efficiency planar heterojunction perovskite solar cell produced by using 4-morpholine ethane sulfonic acid sodium salt doped SnO2

Perovskite solar cells (PSCs) have become a promising photovoltaic (PV) technology. Meanwhile, developing an electron transport layer (ETL) has been an effective way to promote the power conversion efficiency (PCE) of PSCs. Here, a 4-morpholine ethane sulfonic acid sodium salt (MES Na+) doped SnO2 ETL is utilized in planar heterojunction PSCs. The results show that the MES Na+ doped ETL can improve the crystallinity, and absorbance of perovskite films, and passivate interface defects between the perovskite film and SnO2 ETL. The doping effect accounts for the enhancement of conductivity and the decreasing work function of SnO2. When 10 mg mL−1 MES Na+ was added to the SnO2 precursor solution, the device showed the best performance Jsc, Voc, and FF of the PSCs values, which were 23.88 mA cm−2, 1.12 V and 78.69%, respectively, and the PCE was increased from 17.43% to 21.05%. This doping ETL strategy provides an avenue for defect passivation to further increase the efficiency of perovskite solar cells.