Organometallic halide perovskite films with good surface morphology and large grain size are desirable for obtaining high‐performance photovoltaic devices. However, defects and related trap sites are generated inevitably at grain boundaries and on surfaces of solution‐processed polycrystalline perovskite films. Seeking facial and efficient methods to passivate the perovskite film for minimizing defect density is necessary for further improving the photovoltaic performance. Here, a convenient strategy is developed to improve perovskite crystallization by incorporating a 2D polymeric material of graphitic carbon nitride (g‐C3N4) into the perovskite layer. The addition of g‐C3N4 results in improved crystalline quality of perovskite film with large grain size by retarding the crystallization rate, and reduced intrinsic defect density by passivating charge recombination centers around the grain boundaries. In addition, g‐C3N4 doping increases the film conductivity of perovskite layer, which is beneficial for charge transport in perovskite light‐absorption layer. Consequently, a champion device with a maximum power conversion efficiency of 19.49% is approached owing to a remarkable improvement in fill factor from 0.65 to 0.74. This finding demonstrates a simple method to passivate the perovskite film by controlling the crystallization and reducing the defect density.

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A powerful sorbent of Li+, flower-like MoS2 nanocrystals, was doped into the Spiro-OMeTAD layer for highly efficient and stable perovskite solar cells.

TiO-based nanorods (TNRs) were self-assembled on large graphitic carbon nitride (g-CN) sheets via the solvothermal-assisted route. The results demonstrated that the effective anchoring of TNRs (a side length of ca. 200-300 nm) was highly dispersed on the surface of whole g-CN sheets. The shift in the Ti 2p XPS core level spectrum indicated an increase in the net positive charge of the Ti ions, ensuring the formation of an interface between TNRs and g-CN. The charge transferred from g-CN sheets to TNRs effectively prevented the recombination of excited charges, which is consistent with the significant quenching of PL. The extent of visible-light-sensitive photocatalytic (PC) activity was evaluated by the removal of potassium dichromate (Cr(vi)) or the degradation of rhodamine B (RhB). The photocatalytic removal of Cr(vi) using RhB was effectively improved. The synergistic effect between the removal of Cr(vi) and degradation of RhB was revealed by multiple utilization of TNRs/g-CN for PC activity. The effective suppression of the recombination of photo-induced charges and the absorption of RhB was responsible for the enhancement in the PC activity. An alternate mechanism for enhanced visible-light photocatalytic activity was also considered.