The design of catalysts that are both highly active and stable is always challenging. Herein, we report that the incorporation of single metal active sites attached to the nitrogen atoms in the basal plane of graphene leads to composite materials with superior activity and stability when used as counter electrodes in dye-sensitized solar cells (DSSCs). A series of composite materials based on different metals (Mn, Fe, Co, Ni, and Cu) were synthesized and characterized. Electrochemical measurements revealed that CoN4 /GN is a highly active and stable counter electrode for the interconversion of the redox couple I(-) /I3 (-) . DFT calculations revealed that the superior properties of CoN4 /GN are due to the appropriate adsorption energy of iodine on the confined Co sites, leading to a good balance between adsorption and desorption processes. Its superior electrochemical performance was further confirmed by fabricating DSSCs with CoN4  /GN electrodes, which displayed a better power conversion efficiency than the Pt counterpart.

In the last few years, organometal halide perovskites (OHPs) have emerged as a promising candidate for photovoltaic (PV) applications. A certified efficiency as high as 23.7% has been achieved, which is comparable with most of the well-established PV technologies. Their good solubility due to the ionic nature enables versatile low-temperature solution processes, including blade coating, slot-die coating, etc., most of which are scalable and compatible with roll-to-roll large-scale manufacturing processes. The low cost, high efficiency, and facile processable features make perovskite solar cells (PSCs) a very competitive PV technology. Despite the great progress, long-term durability concerns, toxicity issues of both materials and manufacturing process, and lack of robust high-throughput production technology for fabricating efficient large-area modules are major obstacles toward commercialization. In this review, the recent progress of commercially available process of PSCs is surveyed, the underlying determinants for upscaling high-quality PSCs from hydrodynamic characteristics and crystallization thermodynamic mechanism are identified, the influence of external stress factors on stability of PSCs and intrinsic instability mechanism in OHPs themselves is revealed, and the environmental impact and sustainable development of PSC technology are analyzed. Strategies and opportunities for large-scale production of PSCs are suggested to promote the development of PSCs toward commercialization.blade coating, slot-die coating, screen printing, inkjet printing, etc.), most of which are scalable and compatible with roll-toroll (R2R) large-scale manufacturing processes. We can even image to produce solar cells as simple as printing newspapers or painting the walls. The low cost, high efficiency, and facile processing features make PSCs a potentially transformative PV technology. Despite the incredible progress in PSCs, there are still several obstacles on their way toward commercialization, including scaling up for fabricating efficient large-area modules, long-term durability concerns, and toxicity issues of both materials and manufacturing process.In this review, we survey recent developments in the field of fabricating commercially available PSCs from three critical issues: first, the progress related to fabrication of large-area PSCs will be summarized, and a detailed discussion regarding the hydrodynamic characteristics and crystallization thermodynamic mechanism for growth of high-quality large-area perovskites will be provided; second, stability issues of perovskites will be discussed, and strategies to improve the stability of perovskites will be summarized; third, environmental impacts of both materials and manufacturing process for PSCs will be discussed, and strategies with respect to fabricating PSCs with greener materials and fabrication routes will be proposed.

The unstable feature of the widely employed organic hole‐transporting materials (HTMs) (e.g., spiro‐MeOTAD) significantly limits the practical application of perovskite solar cells (PSCs). Therefore, it is desirable to design new structured PSCs with stable HTMs presenting excellent carrier extraction and transfer properties. This work demonstrates a new inverted PSC configuration. The new PSC has a graded band alignment and bilayered inorganic HTMs (i.e., compact NiOx and mesoporous CuGaO2). In comparison with planar‐structured PSCs, the mesoporous CuGaO2 can effectively extract holes from perovskite due to the increased contact area of the perovskite/HTM. The graded energy alignment constructed in the ultrathin compact NiOx, mesoporous CuGaO2, and perovskite can facilitate carrier transfer and depress charge recombination. As a result, the champion device based on the newly designed mesoscopic PSCs yields a stabilized efficiency of ≈20%, which is considered one of the best results for inverted PSCs with inorganic HTMs. Additionally, the unencapsulated PSC device retains more than 80% of its original efficiency when subjected to thermal aging at 85 °C for 1000 h in a nitrogen atmosphere, thus demonstrating superior thermal stability of the device. This study may pave a new avenue to rational design of highly efficient and stable PSCs.