Efficient Flexible Perovskite Solar Cells Research Articles

Chemical bath deposition of SnO2 films on PEN/ITO substrates for efficient flexible perovskite solar cells

Flexible perovskite solar cells (f-PSCs) have achieved significant success. However, high-quality tin dioxide (SnO2) electron transport layers (ETLs) fabricated via chemical bath deposition (CBD) have not been achieved on flexible PEN/ITO substrates. This limitation is primarily due to the corrosion of the poor-quality ITO layer by the strongly acidic CBD solution. Here, we analyzed the reasons for the poor corrosion resistance of ITO films on PEN substrate from multiple perspectives, such as element composition, microstructure, and crystallinity. Then, we proposed a modified CBD method for SnO2 films suitable for flexible PEN/ITO substrates. We employed SnCl2·2H2O as the tin source and regulated the pH of the CBD solution by NH3·H2O, which effectively avoided the corrosion of the ITO layer by the CBD solution and achieved high-quality SnO2 films on the ITO layers. Compared to the commercial SnO2 dispersion, the SnO2 films prepared by this method have smaller grains and higher transmittance. As a result, we achieved an unprecedented power conversion efficiency (PCE) of 20.71% for f-PSCs fabricated on PEN/ITO substrates with SnO2 ETLs by CBD method. This breakthrough facilitates the development of high-performance f-PSCs by a low-cost and large-scale chemical bath deposition of high-quality ETLs on flexible substrates.

Silane Doping for Efficient Flexible Perovskite Solar Cells with Improved Defect Passivation and Device Stability.

In this work, doping 3-amino-propyl triethoxysilane (APTES) into a perovskite precursor is proven to be an effective strategy, which can passivate crystal defects, control the crystallization rate, and improve the morphology. APTES can form oligomers through hydrolysis and a condensation reaction, thus blocking the invasion of external water molecules. In addition, the lone pair electrons on the N atom in the amino group of APTES form a coordination bond with perovskite by sharing the empty 6p orbital on Pb2+, which can effectively passivate the defects of the film and realize a highly uniform and dense perovskite film with preferential crystal growth orientation. The film exhibits high (110) crystal plane orientation and long carrier lifetime and mobility, which improves the performance of flexible perovskite solar cells. Using this approach, the champion device presents an optimal power conversion efficiency of 19.84% with much promoted air stability. Moreover, the efficiency of flexible devices does not decrease after maximum power point irradiation for 360 s.

Fabrication of high-performance flexible perovskite solar cells based on synergistic passivation strategy

Flexible perovskite solar cells have attracted much attention in the scientific community due to their lightweight nature, high flexibility, and superior power-to-mass ratio. One of the most effective strategies for enhancing the power conversion efficiency of these cells involves addressing grain boundary defects within the perovskite films and interfacial defects between the perovskite films and charge transport layers. In this work, we optimize the performance of inverted flexible perovskite solar cell by using octadecylamine hydrochloride (OACl) as both an additive and a surface passivating agent to achieve synergistic passivation to the bulk phase and surface. The incorporation of OACl in the perovskite precursor solution results in the enlarging of the perovskite crystal grains, enhancing crystallinity, and passivating of grain boundary defects within the perovskite film. This optimization leads the open-circuit voltage to increase from 1.07 to 1.12 V, fill factor from 70.86% to 75.04%, and power conversion efficiency from 18.08% to 20.12%. In addition, the OACl solution is used to passivate the surface of perovskite film, resulting in a smoother perovskite surface, fill the grain boundaries, and reduce the defect density on the perovskite surface. As a result, the optimized device exhibits an open-circuit voltage of 1.15 V, fill factor of 76.15%, and ultimately achieves a power conversion efficiency of 20.80% for flexible perovskite solar cells. The synergistic passivation strategy based on OACl used in this work provides an effective approach for fabricating efficient flexible perovskite solar cells.

Self-healing ion-conducting elastomer towards record efficient flexible perovskite solar cells with excellent recoverable mechanical stability

The flexible PSCs with ionic conductive elastomers achieved a record efficiency of 24.84% and self-repaired the cracks at 25 °C.

EXPLORING EFFICIENCY AND DESIGN OPTIMIZATION OF FLEXIBLE PEROVSKITE SOLAR CELLS USING SCAPS-1D SIMULATION

This research focuses on using SCAPS-1D software to design and simulate efficient flexible perovskite solar cells. The study aims to optimize design parameters, gain a deeper understanding of the underlying physics, and obtain valuable insights into electrical characteristics. The device architecture includes key components like PET/ITO substrate, TiO2 ETL, CH3NH3SnI3 absorber, CuSCN HTL, and Au electrode. By optimizing the absorber thickness (600 nm) and temperature (300 K), the performance and efficiency of the cell were improved. Investigation of different doping concentrations at 300 K for a fixed thickness revealed an efficiency of 26.98% at 600 nm. The highest efficiency of 31.44% was achieved with a doping concentration of 1E+21. This research showcases the potential of flexible perovskite solar cells for lightweight and versatile applications, emphasizing their significance in the field.

Synthesizing and characterization of Lead Halide Perovskite Nanocrystals solar cells from reused car batteries

With the rapid increase of efficiency up to 23.7% during the past few years, hybrid organic-inorganic metal halide perovskite solar cells (PSCs) have become a research “hot spot” for many solar cell researchers. The perovskite materials show various advantages due to unique characteristics of perovskite materials, such as high photo-to-electric conversion efficiency, direct band gap, high light absorption coefficient, high charge-carrier mobility and long electron-hole electron transport distance. The low-cost fabrication techniques together with the high efficiency makes PSCs comparable with Si-based solar cells. This paper begins with the discussion of crystal structures of perovskite based on recent research findings. The following part of this paper discussion of synthetic process of lead iodide perovskite materials from lead-acid battery and Harvesting material from the anodes and cathodes of car battery; synthesizing PbI2 from the collected materials and compare with pure Lead iodide to know the absolute by XRD peak, depositing lead iodide perovskite nanocrystals. Efficient flexible PSCs are fabricated onto FTO glass substrate by a two-step coating method under ambient condition. By adjusting the concentration of precursor CH3NH3I (MAI), the morphology and thickness of perovskite layer is effectively tailored, according to SEM analysis and using TiO2 as electron transport layer instead of ZnO and CuI instead of spiro-OMeTAD as hole transport layer.

Highly Efficient Flexible Perovskite Solar Cells through Pentylammonium Acetate Modification with Certified Efficiency of 23.35.

Among the emerging photovoltaic technologies, rigid perovskite solar cells (PSCs) have made tremendous development owing to their exceptional power conversion efficiency (PCE) of up to25.7%. However, the record PCE of flexible PSCs (≈22.4%) still lags far behind their rigid counterparts and their mechanical stabilities are also not satisfactory. Herein, through modifying the interface between perovskite and hole transport layer via pentylammonium acetate (PenAAc) molecule a highly efficient and stable flexible inverted PSC is reported. Through synthetic manipulation of anion and cation, it is shown that the PenA+ and Ac- have strong chemical binding with both acceptor and donor defects of surface-terminating ends on perovskite films. The PenAAc-modified flexible PSCs achieve a record PCE of23.68% (0.08 cm2 , certified: 23.35%) with a high open-circuit voltage (VOC ) of1.17V. Large-area devices (1.0 cm2 ) also realized an exceptional PCE of21.52%. Moreover, the fabricated devices show excellent stability under mechanical bending, with PCE remaining above91% of the original PCE even after5000 bends.

Photovoltaic performance of flexible perovskite solar cells under bending state

Although flexible perovskite solar cells have made extensive progress, there is a lack of investigation on the performance of flexible perovskite solar cells under bending state. Here, two-dimensional models of flexible perovskite solar cells have been performed to reveal the effect of bending angles and directions for the first time. Simulated results are in good agreement with experimentally reported data, validating the accuracy of our model. To optimize mechanical and optical performance under bending state, silica subwavelength array is embedded on the surface of the flexible substrate. Hence, the current density of flexible perovskite solar cells has been improved by 7.3% at downwards bending 60° and 1.9% at upwards bending 60°. Our work provides a guide for the design of efficient flexible perovskite solar cells under bending state.

Thermally driven self-healing efficient flexible perovskite solar cells

The brittleness of perovskite (PVK) film restrains the development and application of the flexible perovskite solar cells (FPSCs). We utilize the polyurethane elastomers with disulfide bonds (PUDS) as a self-healing polymer to construct self-healing FPSCs and strengthen the self-healed perovskite film by the phase-locked state. The PUDS efficiently enhances the flexibility and self-healing properties of FPSCs. The champion efficiencies of MAPbI3 on rigid and flexible substrates with PUDS are 20.30% and 17.19%, respectively. Importantly, the efficiency of cracked FPSC after thermal self-healing (80 °C) has been recovered from 12% (Broken: 2.06%) of the initial efficiency (17.19%) to 88% (Recovery: 15.12%). Besides, the efficiency of FPSC with PUDS maintains 95% of the initial value after 3000 h stored in glove box. This strategy provides an effective approach for developing flexible electronics.

Efficient Flexible Perovskite Solar Cells with Reduced Hysteresis Employing Cobalt Nitrate Treated SnO2

Flexible perovskite solar cells (PSCs) have great potential for portable electronics, however, suffer from large hysteresis in regular structure. Insufficient charge extraction in commonly used tin dioxide (SnO2) electron transporting layer (ETL) is regarded as one possible origin of hysteresis due to the low crystallinity and energy level mismatching. Here, the hysteresis of flexible PSCs is suppressed by synthesizing cobalt‐modified SnO2 ETLs, which improve electron extraction capability due to the high carrier mobility and well‐aligned energy levels. Moreover, cobalt modification passivates the defects on the ETL surface, facilitates sequential perovskite film growth, and inhibits carrier recombination. As a result, flexible PSCs with efficiencies exceeding 20% are obtained with significantly reduced hysteresis and enhanced illumination stability. Comprehensive optoelectronic simulations are conducted to unveil the deep mechanisms of eliminated hysteresis. The proposed work provides an efficient and facile strategy for the fabrication of high‐performance flexible PSCs upon future commercialization.

Self-healing and efficient flexible perovskite solar cells enabled by host–guest interaction and a 2D/3D heterostructure

Thein situsynthesis of a ternary polymer (TPP polymer) to construct host–guest interaction between GMA-CD and N-AA and a 2D/3D heterostructure supports the development of efficient, stable, self-healing and flexible perovskite solar cells.

NdCl3 Dose as a Universal Approach for High-Efficiency Perovskite Solar Cells Based on Low-Temperature-Processed SnOx

The defects on the surface of low-temperature-processed electronic transport layers hindered the development of efficient flexible perovskite solar cells. Herein, we develop a universal NdCl3 dosing strategy to circumvent the residual Sn(II)-OH defects from the incomplete wet-chemical reaction. The introduction of NdCl3 does not lead to the doping of Nd3+ ions but rather the formation of a composite film of NdCl3 with SnOx. The dose of NdCl3 effectively reduces surface trap states at low-temperature-processed SnOx films, leading to increased carrier extraction and reduced carrier accumulation/recombination at the ETL/perovskite interface. These improvements result in perovskite solar cells (PvSCs) with significantly enhanced power conversion efficiency (PCE) and eliminated hysteresis. Finally, efficiencies of 18.62% and 21.49% for PvSCs based on MAPbI3 and FA1-xMAxPbI3 perovskites, respectively, were achieved on rigid substrates. The test on a flexible device based on Cs0.05(FA0.83MA0.17)0.95(I0.83Br0.17)3 perovskite realized a PCE of 16.14% and an incredible VOC of 1.158 V. This study indicated the potential of NdCl3 dose as a universal approach to enhance the performance of PvSCs with low-temperature-processed SnOx ETL.

Rational Interface Design and Morphology Control for Blade‐Coating Efficient Flexible Perovskite Solar Cells with a Record Fill Factor of 81%

AbstractHalide perovskites are one of the ideal photovoltaic materials for constructing flexible solar devices due to relatively high efficiencies for low‐temperature solution‐processed devices. However, the overwhelming majority of flexible perovskite solar cells are produced using spin coating, which represents a major hurdle for upscaling. Here, a scalable approach is reported to fabricate efficient and robust flexible perovskite solar cells on a polymer substrate. Thiourea is introduced into perovskite precursor solution to modulate the crystal growth, resulting in dense and uniform perovskite thin films on rough surfaces. As a decisive step, a cascade energy alignment is realized for the hole extraction layer by rationally designing a bilayer interface comprised of PEDOT:PSS/PTAA with a distinct offset in the highest occupied molecular orbital levels, enabling markedly enhanced charge extraction and spectral response. An efficiency as high as 19.41% and a record fill factor up to 81% are achieved for flexible perovskite devices processed by a scalable printing method. Equally important, the bilayer interface reinforces the bendability of the indium tin oxide substrate, leading to enhanced mechanical robustness of the flexible devices. These results underpin the importance of morphology control and interface design in constructing high‐performance flexible perovskite solar cells.

Highly efficient flexible perovskite solar cells made via ultrasonic vibration assisted room temperature cold sintering

With emerging flexible substrates, perovskite solar cells have entered into a new stage of development toward flexibility, portability and miniaturization. However, this promising landscape is hindered by the necessity the high-temperature processes. In this study, a highly efficient, stable and flexible planar perovskite solar cell is fabricated using an all-room temperature pathway. First, a nanocrystalline SnO2 layer is deposited on polyethylene terephthalate/indium tin oxide via room-temperature sol-gel strategy. Then (FAPbI3)0.85(MAPbBr3)0.15 is coated thereon, by annealing-free solution deposition. In both steps films are subjected to ultrasonic vibration, right after deposition, while they are still wet. By virtue of the ultrasonic energy, surface evaporation of liquid molecules is accelerated, impurities are removed from deposited wet film, and as a result shrinkage and sintering occur at room temperature. The cell is completed by a classical method, showing a champion power conversion efficiency of 17.38%, based on 0.16 cm2 active area. After 480 h aging in 50% relative humidity, this cell retains 80% of its initial performance. This research promises efficient, inexpensive and sustainable systems for harvesting solar energy by wearable modules.

Energy Level-Graded Al-Doped ZnO Protection Layers for Copper Nanowire-Based Window Electrodes for Efficient Flexible Perovskite Solar Cells.

Flexible perovskite solar cells (PSCs) have attracted significant interest as promising candidates for portable and wearable devices. Copper nanowires (CuNWs) are promising candidates for transparent conductive electrodes for flexible PSCs because of their excellent conductivity, flexibility, and cost-effectiveness. However, because of the thermal/chemical instability of CuNWs, they require a protective layer for application in PSCs. Previous PSCs with CuNW-based electrodes generally exhibited poor performances compared with their indium tin oxide-based counterparts because of the neglect of the interfacial energetics between the electron transport layer (ETL) and CuNWs. Herein, an Al-doped ZnO (AZO) protective layer fabricated using atomic layer deposition is introduced. The AZO/CuNW-based composite electrode exhibits improved thermal/chemical stability and favorable band alignment between the ETL and CuNWs, based on the Al dopant concentration tuning. As a result, the Al content gradient AZO (g-AZO), composed of three successively deposited AZO layers, leads to highly efficient flexible PSCs with a power conversion efficiency (PCE) of 14.18%, whereas the PCE of PSCs with a non-g-AZO layer is 12.34%. This improvement can be attributed to the efficient electron extraction and reduced charge recombination. Furthermore, flexible PSCs based on g-AZO-based composite electrodes retain their initial PCE, even after 600 bending cycles, demonstrating excellent mechanical stability.

Efficient flexible perovskite solar cells based on a polymer additive

The rapid development of flexible perovskite solar cells (FPSCs) has attracted more and more attention. The application of FPSCs is largely in thrall to the fragility of perovskite crystals and quality of perovskite films caused by the inherent nature and uncertain grain size of perovskite. A polymer additive as an efficient strategy is utilized to restrict the fragility and improve the durability of FPSCs. In this work, we use polycaprolactone (PCL) as a polymer additive to achieve the grain boundary regulation (improving the grain size) and the desirable mechanical strength of FPSCs. A champion device based on glass/indium tin oxide (ITO) achieves high photoelectric conversion efficiency (PCE) (14.49%), which is ∼37.7% higher than that of the pristine film (10.52%). While the efficiency of FPSCs also retains 9.11%, which is 90% of the initial PCE (10.12%) after 300 bending cycles. Importantly, the PCL as a polymer additive shows great potential for future applications in wearable electronics.

A novel 2D perovskite as surface “patches” for efficient flexible perovskite solar cells

High-efficiency flexible perovskite solar cells based on a novel mixed-cation 2D perovskite passivating FA-based perovskite absorber.

Highly efficient flexible perovskite solar cells and their photo-stability

We report a simple method to fabricate highly efficient and robust flexible perovskite solar cells (F-PSCs) along with their photo-stability. The solar cells were prepared on indium tin oxide (ITO) coated polyethylene terephthalate substrates. The solar cells incorporated methylammonium lead iodide chloride (CH3NH3PbI3−xClx) perovskite as the light absorber, tin oxide (SnO2) as the electron transport layer (ETL), Spiro-MeOTAD as the hole transport layer and Ag as the top electrode. This structure exhibited a very high external quantum efficiency (EQE) of ~80% at 500 nm and a power conversion efficiency (PCE) of 12.7% ± 0.6% (active area 9.6 mm2) with multiple bending cycles showing no effect on the performance, even after 100 bending cycles. To evaluate their lifetime in the dark and under actual operating conditions, a systematic study was performed on the unsealed devices. The solar cells showed a halflife (T50) of about 340 h when stored in the dark in an ambient environment, but they degraded very rapidly in direct sunlight. The main reason behind their degradation was found to be the rapid degradation in their short circuit current density (Jsc). The same device design was processed to fabricate large area flexible solar modules with an area of 5 × 5 cm2 (active area 15.84 cm2) and the solar modules exhibited PCE of 5.6% ± 0.2%. Substantial loss of PCE in the modules compared to small area devices has been attributed to the larger series resistance of the longer ITO electrodes used in the modules.

Interconnected SnO2 Nanocrystals Electron Transport Layer for Highly Efficient Flexible Perovskite Solar Cells

This study reports on interconnected SnO2 electron transport layers (composed of presynthesized SnO2 nanocrystals interconnected by amorphous phase SnOx) processed at low temperature (120 °C) for highly efficient flexible perovskite solar cells. Herein, the amorphous phase SnOx serves as an effective binder to connect the SnO2 nanocrystals to obtain ultra‐smooth electron transport layers. Further characterization of the charge carrier kinetics at the perovskite/electron transport layer interface confirms that the interconnected SnO2 nanocrystals layer facilitates electron extraction and retards nonradiative charge carrier recombination. Consequently, a power conversion efficiency of 16.29% is achieved for flexible perovskite solar cells using the interconnected SnO2 electron transport layer on indium tin oxide/polyethylene terephthalate substrates.

Perovskite Grains Embraced in a Soft Fullerene Network Make Highly Efficient Flexible Solar Cells with Superior Mechanical Stability.

Halide perovskite films processed from solution at low-temperature offer promising opportunities to make flexible solar cells. However, the brittleness of perovskite films is an issue for mechanical stability in flexible devices. Herein, photo-crosslinked [6,6]-phenylC61 -butyric oxetane dendron ester (C-PCBOD) is used to improve the mechanical stability of methylammonium lead iodide (MAPbI3 ) perovskite films. Also, it is demonstrated that C-PCBOD passivates the grain boundaries, which reduces the formation of trap states and enhances the environmental stability of MAPbI3 . Thus, MAPbI3 perovskite solar cells are prepared on solid and flexible substrates with record efficiencies of 20.4% and 18.1%, respectively, which are among the highest ever reported for MAPbI3 on both flexible and solid substrates. The result of this work provides a step improvement toward stable and efficient flexible perovskite solar cells.