Solid state hybrid solar cells with hybrid organolead halide perovskites (CH 3 NH 3 PbBr 3 and CH 3 NH 3 PbI 3 ) as light harvesters and p-type polymer poly[N-9-hepta-decanyl-2,7-carbazole-alt-3,6-bis-(thiophen-5-yl)-2,5-dioctyl-2,5-di-hydropyrrolo [3,4-]pyrrole-1,4-dione](PCBTDPP) as a hole transporting material were studied. The Great attention has recently been drawn to developing costeffective, high efficiency solar cells to meet the ever increasing demand for clean energy. Dye/semiconductor sensitized solar cells, 1-11 organic solar cells, 12-15 and inorganic-organic hybrid solar cells [16][17][18][19][20][21] show promise among the novel photovoltaic devices. However, liquid electrolyte-based sensitized solar cells suffer from solvent leakage, and organic solar cells have the problem of short life-time. Hybrid solar cells present a possibility to overcome these disadvantages by using solid-state ptype hole transporting materials (HTM) in lieu of the liquid electrolyte.22-28 Most recently, research in this eld has achieved great progress: PCEs exceeding 5% have been obtained for solar cells consisting of Sb 2 S 3 nanocrystals as the sensitizer, mesoscopic TiO 2 as the n-type electron transporting material (ETM) and p-type polymers as the HTM. 29,30Hybrid organolead halide perovskites are a class of semiconductors with ABX 3 (X ¼ Cl À , Br À , and I À ) structures consisting of lead cations in 6-fold coordination (B site), surrounded by an octahedron of halide anions (X site, face centered) together with the organic components in 12-fold cuboctahedral coordination (A site) (Fig. 1a). Their intrinsic properties can easily be tuned by tailoring the chemistry of the organic and inorganic components. 31,32 These hybrid perovskites have a direct band gap, a large absorption coefficient as well as high carrier mobility. Especially notable is that they can be synthesized by simple solution approaches, a very attractive characteristic for fabricating cost-effective solar cells. Miyasaka et al. 33 have pioneered their application in sensitized solar cells in a liquid electrolyte system, and a high efficiency of 6.5% was reported later. Unfortunately the performance of the solar cells degraded very rapidly due to the dissolution of perovskite sensitizers in the liquid electrolyte.34 A breakthrough was

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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.

Planar perovskite solar cells (PSCs) have attracted extensive research attention owing to their simple architecture and manufacturing process. Improving the charge extraction ability of the electron transport materials (ETMs) is...

Instability of emerging perovskite organometallic halide in humidity environment is the biggest obstacle for its potential applications in solar energy harvest and electroluminescent display. Understanding the detailed decay mechanism of these materials in moisture is a critical step towards the final appropriate solutions. As a model study presented in this work, in situ synchrotron radiation x-ray diffraction was combined with microscopy and gravimetric analysis to study the degradation process of CH3NH3PbI3 in moisture, and the results reveal that: 1) intermediate monohydrated CH3NH3PbI3·H2O is detected in the degradation process of CH3NH3PbI3 and the final decomposition products are PbI2 and aqueous CH3NH3I; 2) the aqueous CH3NH3I could hardly further decompose into volatile CH3NH2, HI or I2; 3) the moisture disintegrate CH3NH3PbI3 and then alter the distribution of the decomposition products, which leads to an incompletely-reversible reaction of CH3NH3PbI3 hydrolysis and degrades the photoelectric properties. These findings further elucidate the picture of hydrolysis process of perovskite organometallic halide in humidity environment.

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It is essential to minimize the interfacial trap states and improve the carrier collection for high efficiency perovskite solar cells (PSCs). Herein, we present a facile method to construct a p-type graded heterojunction (GHJ) in normal PSCs by deploying a gradient distribution of hole-transporting materials (poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], PTAA, in this case) in the shallow perovskite layer. The formation of the GHJ structure facilitates charge transfer and collection, and passivates interfacial trap states, thus delivering a power conversion efficiency (PCE) of 20.05 % along with steady output efficiency of 19.3 %, which is among the highest efficiencies for cesium formamidinium (Cs-FA) lead halide PSCs. Moreover, the unencapsulated devices based on these (Cs-FA) lead halide perovskites show excellent long-term stability; more than 95 % of their initial PCE can be retained after 1440 h storage under ambient conditions. This study may provide an effective strategy to fabricate high-efficiency PSCs with great stability.

A facile solution-phase route was developed to synthesize a family of monodisperse Cu 2 Ge(S 3−x Se x ) alloyed nanocrystals (NCs) with controlled composition across the entire range (0 ≤ x ≤ 3). The band gaps of the resultant NCs can be engineered by tuning the compositions with a nearly linear relationship between them. The band structures of the NCs were studied by cyclic voltammetry and UV−vis absorption spectroscopy. The conducting behavior was revealed to be p-type for these NCs by photoelectrochemical measurements. Their photovoltaic applicability was finally assessed by fabricating solar cells with the Cu 2 Ge(S 2 Se) NCs as light harvester and CdS nanorods as electron conducting materials. C olloidal semiconductor nanocrystals (NCs) are of great interest due to their unique optical, magnetic, and electronic properties that are not achieved by their bulk counterparts. These NCs show advantages in low-cost synthesis and simple postprocessing, tunable properties, and high device performance. Colloidal semiconductor NCs have a wide range of applications in photovoltaics, 1 light-emitting diodes (LEDs), 2 bioimaging, 3 and so on. It has become increasingly facile to precisely control their size, shape, and crystal structure 4−6 for binary semiconductor NCs by colloidal synthesis, significantly promoting studies into their applications. Extension of colloidal synthesis to ternary and even quaternary semiconductor NCs may greatly expand this research platform. Moreover, the ability to tune the properties, especially band gap, to a target value is critical in achieving high-performance devices. However, this remains a big challenge for multicomponent semiconductor NCs. It is currently of great interest, but very limited successes have been reported in fabricating multicomponent NCs with properties that are consecutively tunable. To this end, growth of multicomponent NCs by alloying two constituents to produce desired alloyed NCs with tunable composition and properties has been described in several cases.7−12 The alloyed NCs may not only inherit the properties of their parent materials but also exhibit new properties distinct from them.7 Additionally, beside the size-dependent quantum confinement effect, the band gap energy of semiconductor NCs can be effectively tuned by varying their compositions via alloying of the constituents.As environmentally friendly materials with the capability of band gap tailoring in a wide range, the Cu-based ternary and quaternary chalcogenides have received considerable interest in electronics. High-quality NCs of the Cu-based multicomponent