Search

Ultra‐thin stainless‐steel substrates with excellent water‐oxygen barrier properties and high thermal and electrical conductivities are suitable for the fabrication of lightweight and flexible perovskite solar cells (FPSCs). However, the deposition of dense perovskite films on stainless steel by the solution method is crucial because short circuits caused by perovskite holes are fatal to parallel structures. Herein, a single crystal (SC) is incorporated into the precursor solution to reduce the formation of holes in perovskite films on smooth stainless‐steel substrates. Additionally, a magnetic method is developed based on the properties of stainless steel to fix and fabricate FPSCs nondestructively on ultra‐thin stainless‐steel films with a thickness as low as 5 μm. Furthermore, 4,6‐dimethyl‐2‐mercaptopyrimidine (DMI) was introduced to passivate the surface of the perovskite film, optimizing the contact properties of the perovskite heterojunction and adjusting the energy level of the perovskite/C60 interface. Finally, ultra‐thin FPSCs achieved a champion power conversion efficiency (PCE) of 20.24% on an active area of 1.012 cm2 and a power‐to‐weight ratio over 3000 W kg−1. Moreover, under continuous illumination, the stainless‐steel substrates exhibited better photothermal stability than the polymer substrates. This method provides a basis for the fabrication of lightweight, low‐cost, and large‐area FPSCs. [ABSTRACT FROM AUTHOR]

Reducing the interfacial defects between the perovskite/electron transport layer (ETL) is the key point to improving the efficient and stable performance of perovskite solar cells (PSCs). In this study, two self-assembled molecules ((aminomethyl)phosphonic acid and glycine) with different functional groups (phosphonic acid (-H2PO3) and carboxylic acid (-COOH)) were mixed to form the buried bottom interface of PSCs. The synergistic effect of -H2PO3 with its higher anchoring ability and -COOH with its fast carrier transport improved the performance of PSCs. Additionally, the SnO2 modified by mixed self-assembly molecules (M-SAM) showed a more appropriate energy level alignment, favoring charge transport and minimizing energy loss. In addition, the amine group (-NH2) on the two small molecules effectively interacted with uncoordinated Pb2+ in perovskite and improved the quality of the perovskite films. Consequently, the (FAPbI3)0.992(MAPbBr3)0.008 PSCs with M-SAM reached a PCE of 24.69% (0.08 cm2) and the perovskite modules achieved a champion efficiency of 18.57% (12.25 cm2 aperture area). Meanwhile, it still maintained more than 91% of its initial PCE after being placed in nitrogen atmosphere at 25 °C for 1500 h, which is better than that of the single-SAM and control devices. Further reference is provided for the future commercialization of perovskite with efficient and stable characteristics. [ABSTRACT FROM AUTHOR]

Effectively encapsulating perovskite solar cells (PSCs) to enhance the external reliability is the key towards commercialization. We herein propose a facile encapsulation method by introducing conductive ribbons and a polyethylene terephthalate (PET) backsheet on both sides of PSC. Via applying thermoplastic polyolefin (TPO) encapsulant, we implemented PSCs with fine encapsulation, enabling considerable durability in the ambient atmosphere and even with water immersion, demonstrating almost no degradation in the device output, which is ascribed to the low water vapor transmission rate as well as the high chemical stability of TPO. The operation reliability of the encapsulated cell is also significantly increased, maintaining 80% of the initial efficiency after 770 hours' light illumination in an ambient atmosphere. This novel encapsulation route provides a feasible idea for the commercial application of PSCs in the future. [ABSTRACT FROM AUTHOR]

The nucleation and crystallization processes within solution‐processed deposition is key for obtaining perovskite films with high quality. Herein, the synergistic effect of Cs+, ligand solvent (tetramethylene sulfoxide, TMSO), and methylammonium ions (MA+) on nucleation and crystallization procedures of preparing perovskites films is studied. The results reveal that producing α‐phase nuclei in the intermediate‐phase film (a perovskite film formed by removing the solvent before annealing) is the key factor for obtaining α‐phase‐pure perovskites, wherein Cs+ is necessary for reducing the formation energy of the α‐phase. In addition, the nonvolatile ligand (TMSO) is used to inhibit rapid nucleation, because it can form a stable intermediate phase. Furthermore, the introduction of the volatile MA+ cations compound (MACl) combined with Cs+ contributed to the direct formation of α‐phase nuclei in the intermediate‐phase film, and ion exchange (between FA+ and MA+) occurs during the subsequent annealing process, which leads to the formation of large‐grain perovskite film with good crystallinity. Maximum power conversion efficiencies of 22.08% and 16.88% are obtained via this strategy for a perovskite solar cell on a small area (active area: 0.09 cm2) and a perovskite solar module (aperture area: 12.92 cm2), respectively. [ABSTRACT FROM AUTHOR]

As the power conversion efficiency (PCE) of perovskite solar cells (PSCs) is increased to as high over 25%, it becomes pre‐eminent to study a scalable process with wide processing window to fabricate large‐area uniform perovskite films with good light‐trapping performance. A stable and uniform intermediate‐state complex film is obtained by using tetramethylene sulfoxide (TMSO), which extends the annealing window to as long as 20 min, promotes the formation of a high‐quality perovskite film with larger grains (over 400 nm) and spontaneously forms the surface texture to result in an improved fill factor and open‐circuit voltage (Voc). Moreover, the superior surface texture significantly increases the long‐wavelength response, leading to an improved short‐circuit current density (Jsc). As a result, the maximum PCE of 21.14% is achieved based on a simple planar cell structure without any interface passivation. Moreover, a large area module with active area of 6.75 cm2 is assembled using the optimized TMSO process, showing efficiency as high as 16.57%. The study paves the way to the rational design of highly efficient PSCs for potential scaled‐up production. [ABSTRACT FROM AUTHOR]

Perovskite solar cells are sensitive to subtle changes in atmospheric conditions, resulting in problems such as the collapse of the perovskite structure and sharp drops in efficiency. Internal defects are also a big obstacle for high‐quality polycrystalline perovskites. At present, it is difficult to control the density of the trapping sites. By using the bidentate chelating agent thenoyltrifluoroacetone (ttfa), the crystallization kinetics, grain sizes, and crystal defect of Cs‐, methylammonium‐, and formamidinium‐based perovskite materials can be to effectively controlled through a nucleation and growth process for the preparation of perovskite crystals. Crystalline‐state tuning during the crystallization process to obtain better quality perovskite thin films can be achieved with no additional operation, which is suitable for the needs of modern industrial production and management. The chelating agent can effectively passivate the defects in perovskite films, leading to a low defect density and a long charge carrier lifetime. As a result, the ttfa‐passivated perovskite solar cell demonstrated a high power conversion efficiency of 19.70 % with superior stability retention of 64 % of the initial power conversion efficiency after two weeks unencapsulated storage in an adverse atmosphere with approximately 50 % relative humidity. [ABSTRACT FROM AUTHOR]

Titanium oxide (TiO 2) and tin oxide (SnO 2) are the most commonly used electron transport materials for high-efficiency n-i-p perovskite solar cells (PSCs); however, several limiting properties of TiO 2 and SnO 2 adversely affect device performance. This study describes a facile method to synthesize SnO 2 :TiO 2 hybrid nanocrystals (NCs) to construct electron transport layers (ETLs) with the advantageous properties of both SnO 2 and TiO 2 for n-i-p PSCs. The optimized SnO 2 :TiO 2 ETL exhibited better surface morphology, well-matched band alignment, higher direct current conductivity, and enhanced electron extraction and transport compared to pristine TiO 2 and SnO 2 ETLs. Moreover, perovskite films deposited on SnO 2 :TiO 2 ETLs exhibited a higher crystallinity and lower trap-state density than those on TiO 2 or SnO 2 ETLs. Therefore, SnO 2 :TiO 2 -based devices showed high performance (with a power conversion efficiency of 23.19%) and stability (with more than 83% retention of the initial efficiency after 800 h of continuous illumination). This study provides a new method for developing low-cost and efficient ETLs for n-i-p PSCs and confirms that constructing SnO 2 :TiO 2 hybrid ETL is an effective method to fabricate high-efficiency and stable planar perovskite solar cells. [Display omitted] • A facile method was developed to synthesize SnO 2 :TiO 2 hybrid nanocrystals. • The SnO 2 :TiO 2 hybrid ETL exhibited the advantageous properties of both TiO 2 and SnO 2. • Perovskite films deposited on SnO 2 :TiO 2 ETLs exhibited a high crystallinity and low trap-state density. • SnO 2 :TiO 2 -based devices had a PCE of 23.19% with >83% retention after 800 h of continuous illumination. [ABSTRACT FROM AUTHOR]