Recoverable Flexible Perovskite Solar Cells for Next-Generation Portable Power Sources

Cross-Linkable Fullerene Enables Elastic and Conductive Grain Boundaries for Efficient and Wearable Tin-Based Perovskite Solar Cells

Tin-based perovskite solar cells (TPSCs) have received increasing attention due to their low toxicity, high theoretical efficiency, and potential applications as wearable devices. However, the inherent fast and uncontrollable crystallization process of tin-based perovskites results in high defect density in the film. Meanwhile, when fabricated into flexible devices, the prepared perovskite film exhibits inevitable brittleness and high Young's modulus, seriously weakening the mechanical stability. In this work, we design and synthesize a cross-linkable fullerene, thioctic acid functionalized C60 fulleropyrrolidinium iodide (FTAI), which has multiple interactions with perovskite components and can finely regulate the crystallization quality of perovskite film. The obtained perovskite film shows an increased grain size and a more matched energy level with the electron transport material, effectively improving the carrier extraction efficiency. The FTAI-based rigid device achieves a champion efficiency of 14.91 % with enhanced stability. More importantly, the FTAI located at the perovskite grain boundaries could spontaneously cross-link during the perovskite annealing process, which effectively improves the conductivity and elasticity of grain boundaries, thereby giving the film excellent bending resistance. Finally, the FTAI-based wearable device yields a record efficiency of 12.35 % and displays robust bending durability, retaining about 90 % of the initial efficiency after 10,000 bending times.

Ammonium Sulfate to Modulate Crystallization for High-Performance Rigid and Flexible Perovskite Solar Cells

Perovskite solar cells (PSCs) are attracting widespread research and attention as highly promising candidates in the field of electronic photovoltaics owing to their exceptional power conversion efficiency (PCE). However, rigid or flexible PSCs still face challenges in preparing full-coverage and low-defect perovskite films, as well as achieving highly reproducible and highly stable devices. Herein, a multifunctional additive 2-aminoethyl hydrogen sulfate (AES) is designed to regulate the film crystallization and thereby form flat and pinhole-free perovskite films. It is found that the introduction of AES can effectively passivate defects, restrain charge carrier recombination, and then achieve a higher fill factor. As seen with grazing incidence wide-angle X-ray scattering (GIWAXS), this approach does not affect the crystal orientation distribution. It is observed that AES addition shows a universality across different perovskite components since the PCE is improved up to 20.7% for FA0.97MA0.03Pb(I0.97Br0.03)3-AES, 22.85% for Cs0.05FA0.95PbI3-AES, 22.23% for FAPbI2.7Br0.3-AES, and 23.32% for FAPI-AES rigid devices. Remarkably, the non-encapsulated flexible Cs0.05 (FA0.85MA0.15)0.95Pb(I0.85Br0.15)3 device with AES additive delivers a PCE of 20.1% and maintains over 97% of its initial efficiency under ambient conditions (25 ± 5% relative humidity) over 2280 h of aging.

Buried Interface Optimization for Flexible Perovskite Solar Cells with High Efficiency and Mechanical Stability

The power conversion efficiency (PCE) and stability of perovskite solar cells (PSCs) are significantly reduced by defect-induced charge non-radiative recombination. Also, unexpected residual strain in perovskite films leads to an unfavorable impact on the stability and efficiency of PSCs, notably flexible PSCs (f-PSCs). Considering these problems, a thorough and effective strategy is proposed by incorporating phytic acid (PA) into SnO2 as an electron transport layer (ETL). With the addition of PA, the Sn inherent dangling bonds are passivated effectively and thus enhance the conductivity and electron mobility of SnO2 ETL. Meanwhile, the crystallization quality of perovskite is increased largely. Therefore, the interface/bulk defects are reduced. Besides, the residual strain of perovskite film is significantly reduced and the energy level alignment at the SnO2/perovskite interface becomes more matched. As a result, the champion f-PSC obtains a PCE of 21.08% and rigid PSC obtains a PCE of 21.82%, obviously surpassing the PCE of 18.82% and 19.66% of the corresponding control devices. Notably, the optimized f-PSCs exhibit outstanding mechanical durability, after 5000 cycles of bending with a 5 mm bending radius, the SnO2-PA-based device preserves 80% of the initial PCE, while the SnO2-based device only remains 49% of the initial value.

Mechanical Durability and Flexibility in Perovskite Photovoltaics: Advancements and Applications

The remarkable progress in perovskite solar cell (PSC) technology has witnessed a remarkable leap in efficiency within the past decade. As this technology continues to mature, flexible PSCs (F-PSCs) are emerging as pivotal components for a wide array of applications, spanning from powering portable electronics and wearable devices to integrating seamlessly into electronic textiles and large-scale industrial roofing. F-PSCs characterized by their lightweight, mechanical flexibility, and adaptability for cost-effective roll-to-roll manufacturing, hold immense commercial potential. However, the persistent concerns regarding the overall stability and mechanical robustness of these devices loom large. This comprehensive review delves into recent strides made in enhancing the mechanical stability of F-PSCs. It covers a spectrum of crucial aspects, encompassing perovskite material optimization, precise crystal grain regulation, film quality enhancement, strategic interface engineering, innovational developed flexible transparent electrodes, judicious substrate selection, and the integration of various functional layers. By collating and analyzing these dedicated research endeavors, this review illuminates the current landscape of progress in addressing the challenges surrounding mechanical stability. Furthermore, it provides valuable insights into the persistent obstacles and bottlenecks that demand attention and innovative solutions in the field of F-PSCs.

Flexible, Transparent, and Bifacial Perovskite Solar Cells and Modules Using the Wide-Band Gap FAPbBr3 Perovskite Absorber

Perovskite solar cells (PSCs) offer impressive performance and flexibility, thanks to their simple, low-temperature deposition methods. Their band gap tunability allows for a wide range of applications, transitioning from opaque to transparent devices. This study introduces the first flexible, bifacial PSCs using the FAPbBr3 perovskite. We investigated the impact of optimizing electron and hole transport layers on the cells' bifaciality, transparency, and stability. PSCs achieved a maximum power conversion efficiency (PCE) of 6.8 and 18.7% under 1 sun and indoor light conditions (1200 lx), respectively, showing up to 98% bifaciality factor and an average visible transmittance (AVT) of 55%. Additionally, a P1-P2-P3 laser ablation scheme has been developed on the flexible poly(ethylene terephthalate) (PET) substrate for perovskite solar modules showing a PCE of 4.8% and high geometrical fill factor (97.8%). These findings highlight the potential of flexible, bifacial PSCs for diverse applications such as building-integrated photovoltaics (BIPV), agrivoltaics, automotive technology, wearable sensors, and Internet of things (IoT).

Toward the Commercialization of Perovskite Solar Modules

Perovskite (PVSK) photovoltaic (PV) devices are undergoing rapid development and have reached a certified power conversion efficiency (PCE) of 26.1% at the cell level. Tremendous efforts in material and device engineering have also increased moisture, heat, and light-related stability. Moreover, the solution-process nature makes the fabrication process of perovskite photovoltaic devices feasible and compatible with some mature high-volume manufacturing techniques. All these features render perovskite solar modules (PSMs) suitable for terawatt-scale energy production with a low levelized cost of electricity (LCOE). In this review, the current status of perovskite solar cells (PSCs) and modules and their potential applications are first introduced. Then critical challenges are identified in their commercialization and propose the corresponding solutions, including developing strategies to realize high-quality films over a large area to further improve power conversion efficiency and stability to meet the commercial demands. Finally, some potential development directions and issues requiring attention in the future, mainly focusing on further dealing with toxicity and recycling of the whole device, and the attainment of highly efficient perovskite-based tandem modules, which can reduce the environmental impact and accelerate the LCOE reduction are put forwarded.

Organic-Hydrochloride-Modified ZnO Electron Transport Layer for Efficient Defect Passivation and Stress Release in Rigid and Flexible all Inorganic Perovskite Solar Cells

All inorganic CsPbI2Br perovskite (AIP) has attracted great attention due to its excellent resistance against thermal stress as well as the remarkable capability to deliver high-voltage output. However, CsPbI2Br perovskite solar cells (PeSCs) still encounter critical challenges in attaining both high efficiency and mechanical stability for commercial applications. In this work, formamidine disulfide dihydrochloride (FADD) modified ZnO electron transport layer (ETL) has been developed for fabricating inverted devices on either rigid or flexible substrate. It is found that the FADD modification leads to efficient defects passivation, thereby significantly reducing charge recombination at the AIP/ETL interface. As a result, rigid PeSCs (r-PeSCs) deliver an enhanced efficiency of 16.05% and improved long-term thermal stability. Moreover, the introduced FADD can regulate the Young's modulus (or Derjaguin-Muller-Toporov (DMT) modilus) of ZnO ETL and dissipate stress concentration at the AIP/ETL interface, effectively restraining the crack generation and improving the mechanical stability of PeSCs. The flexible PeSCs (f-PeSCs) exhibit one of the best performances so far reported with excellent stability against 6000 bending cycles at a curvature radius of 5 mm. This work thus provides an effective strategy to simultaneously improve the photovoltaic performance and mechanical stability.