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Optical response improvement and hole transport/extraction enhancement are critical to enhancing the power conversion efficiency (PCE) of carbon electrode-based perovskite solar cells (C-PSCs) with an absorber of CsPbBr3. In this study, a multifunctional optimization method by embedding MoS2nanosheets in CsPbBr3bulk to construct a perovskite–nanosheet hybrid structure was presented. A CsPbBr3–MoS2hybrid film was fabricated by two-step spin-coating the precursor solutions of PbBr2and CsBr–MoS2under an ambient atmosphere, where the aqueous solution with highly distributed MoS2nanosheets was applied as a solvent of the hybrid precursor solution. MoS2nanosheets were utilized as a p-type modifier and extra absorber to hybridize with CsPbBr3for improving the CsPbBr3–carbon interface and light absorption ability of the perovskite layer. As expected, the optical response ability, absorber film quality, and carrier separation/extraction/transport properties of C-PSCs were enhanced significantly by embedding MoS2nanosheets in CsPbBr3film, which resulted in enhanced C-PSCs properties. Finally, the C-PSCs with the structure of FTO/SnO2/CsPbBr3–MoS2/C presented a champion PCE of 7.87% (active area: 1 cm2), which demonstrated excellent ambient and operational stability. This study provides an efficient method for constructing ultrastable C-PSCs by hybridizing perovskite and nanosheets.

Regulating strain in perovskite films via utilizing the crystal structure relationship between solid-phase materials (SPMs) and perovskite is an effective method to achieve high-performance perovskite solar cells. It is crucial to investigate and manipulate the heterointerfaces between perovskites and SPMs since the mismatched crystal structure and energy band structure of SPMs will bring recombination sites to the heterointerfaces. In this work, CdS-modified PbS nanosheets (CPS) were prepared through cation exchange with (200)-preferred PbS nanosheets. The wide-band gap CdS charge-blocking layer of CPS nanosheets distributed at the grain boundaries effectively passivates the heterointerfaces in FAPbI3-CPS heterostructures (FAPI-CPS). Further, it potentially blocks carrier transportation and suppresses carrier recombination at grain boundaries and in FAPbI3-PbS nanosheet heterointerfaces. Attributed to the CdS layer, the FAPI-CPS devices achieve an enhanced power conversion efficiency. CPS nanosheets with an interplanar spacing slightly smaller than that of a-FAPbI3could provide compressive strain to FAPbI3at the FAPI-CPS heterointerfaces, leading to significantly improved device stability. The unencapsulated FAPI-CPS solar cells maintained 92% of their initial PCE after being stored at 20 ± 5 °C, 20 ± 5% RH for 2500 h.

Organic–inorganic hybrid perovskites have been emerging as promising light-harvesting materials for high-efficiency solar cells recently. Compared to solution-based methods, vapor-based deposition technologies are more suitable in preparing compact, uniform, and large-scale perovskite thin films. Here, we utilized flash-evaporation printing (FEP), a laser-induced ultrafast single source evaporation method employing a carbon nanotube evaporator, to fabricate high-quality methylammonium lead iodide perovskite thin films. Stoichiometric films with pure tetragonal perovskite phase can be achieved using a controlled methylammonium iodide to lead iodide ratio in evaporation precursors. The film crystallinity and crystal grain growth could further be promoted after postannealing. Planar solar cells (0.06 cm2) employing these perovskite films exhibit a champion power conversion efficiency (PCE) of 16.8% with insignificant hysteresis, which is among the highest reported PCEs using vapor-based deposition methods. Large-area (1 cm2) devices based on such perovskite films also achieved a stabilized PCE of 11.2%, indicating the feasibility and scalability of our FEP method in fabricating large-area perovskite films for other optoelectronic applications.