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Due 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. [ABSTRACT FROM AUTHOR]

The quality of perovskite film plays an important role on the performance and stability of perovskite solar cells (PSCs). Herein, dense and uniform perovskite (CH 3 NH 3 PbI 3 ) films are fabricated by combining hot-casting technique (HCT) and methylamine (CH 3 NH 2 ) gas treatment (MGT) under ambient conditions with a relative humidity of about 60%. These high quality CH 3 NH 3 PbI 3 films are further used to fabricate planar heterojunction (PHJ) PSCs with a structure of ITO/PEDOT:PSS/CH 3 NH 3 PbI 3 /PCBM/Ag, showing a power conversion efficiency ( PCE ) up to 14.2% with negligible hysteresis. More importantly, these PHJ-PSCs show excellent stability, and over 80% of their original efficiencies could be maintained even stored in air (humidity ∼45%) for 20 days without encapsulation. Meanwhile, the PCE up to 13.6% could be achieved for PHJ-PSCs fully fabricated in air including electron transport layer PCBM. The researches provide an ease-of-fabrication method to fully fabricate highly efficient and stable PHJ-PSCs under ambient conditions with high humidity, which would potentially accelerate the commercialization of PHJ-PSCs. [ABSTRACT FROM AUTHOR]

It is highly desirable to develop large‐scale, low‐cost fabrication processes for flexible perovskite solar cells (f‐PSCs) under ambient conditions for accelerating their potential commercialization. Roll‐to‐roll (R2R) printing technology enables high‐output manufacturing and is well suited for commercially processing f‐PSCs. Herein, triple‐cation f‐PSCs are developed with a planar heterojunction structure consisting of polyethylene‐2,6‐naphthalate/indium tin oxide/SnO2/perovskite/spiro‐OMeTAD/Ag via a combination of R2R microgravure printing and slot‐die coating under ambient conditions with a relative humidity of ≈40%. A mixture of isopropanol and water is used to dilute an as‐purchased SnO2 colloid solution and modify the contact between the electron‐transport layer (ETL) and substrate, leading to a smooth morphology of the R2R‐printed ETL SnO2 layer. Furthermore, suitable intrinsic organic salt additives and the N2 gas blowing‐assisted process are introduced to effectively improve the crystallization of the perovskite, resulting in a high‐quality perovskite film via R2R. After the optimization, the f‐PSCs based on the R2R‐printed ETL SnO2 and the perovskite film under an ambient condition show a power conversion efficiency (PCE) of up to 10.56% and an average PCE of 9.97%. This study provides a potential strategy for commercially fabricating f‐PSCs via a scalable and efficient R2R printing process. [ABSTRACT FROM AUTHOR]

It is a great challenge to process highly efficient perovskite solar cells (PSCs) under ambient conditions, which limits their potential commercialization. Herein, high‐quality triple cation mixtures Cs0.21FA0.56MA0.23(I0.98Br0.02)3 perovskite films are fabricated through two‐step solution processes via in situ substrate‐heating‐assisted deposition under ambient conditions with a relative humidity of about 40%. The in situ substrate temperature during the deposition significantly influences the grain size and compactness of lead iodide films, and therefore greatly affects the morphology, composition, and band gap of resulted perovskite films. Based on the optimization of substrate temperature and the thickness of perovskite layer, PSCs with a planar heterojunction configuration of ITO/SnO2/perovskite/Spiro‐OMeTAD/Ag are fabricated, which deliver a power conversion efficiency up to 18.38%. These results suggest that high‐performance PSCs can be fabricated under ambient conditions instead of an inert environment, providing a fundamental step for accelerating PSC commercialization. High‐quality perovskite films are fabricated via in situ substrate‐heating‐assisted deposition in air. The in situ substrate temperature significantly influences the morphology, composition, and band gap of resulted perovskite films. The perovskite solar cells fabricated in air show the efficiency up to 18.38%. The fabrication process and device structure offer the advantages of well matching with low‐cost, large‐scale printing techniques. [ABSTRACT FROM AUTHOR]