Although inorganic hole-transport materials usually possess high chemical stability, hole mobility, and low cost, the efficiency of most of inorganic hole conductor-based perovskite solar cells is still much lower than that of the traditional organic hole conductor-based cells. Here, we have successfully fabricated high quality CH3NH3PbI3 films on top of a CuSCN layer by utilizing a one-step fast deposition-crystallization method, which have lower surface roughness and smaller interface contact resistance between the perovskite layer and the selective contacts in comparison with the films prepared by a conventional two-step sequential deposition process. The average efficiency of the CuSCN-based inverted planar CH3NH3PbI3 solar cells has been improved to 15.6% with a highest PCE of 16.6%, which is comparable to that of the traditional organic hole conductor-based cells, and may promote wider application of the inexpensive inorganic materials in perovskite solar cells.

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especially critical. The element Pb could be replaced by bismuth (Bi) or antimony (Sb), where the perovskite displays a dimeric structure of A 3 B 2 X 9 (e.g., (CH 3 NH 3 ) 3 Bi 2 I 9 , Cs 3 Sb 2 I 9 ). [17,18] Although these materials have realized full Pb-removal, photovoltaic performance of their devices is so poor that these materials still need to be optimized. Alternatively, another element tin (Sn), which also belongs to the IVA group and has a similar ionic radii to that of Pb (Sn 2+ 1.35 Å and Pb 2+ 1.49 Å), may enable substitution without significant lattice perturbation. [19] Although the toxicity and environmental effect of Sn are less studied, current data indicate that Sn is much easier to be removed from body (less than 400 d) than Pb, which has a long half-life of 20-30 years. [20] The most environmental side-effect of Sn-based perovskite solar cell relies on its low power conversion efficiency, which means much more materials are needed than Pb-based perovskite solar cell. [21] Thus, a high-efficiency Sn-based perovskite solar cell is yet to be explored for competing with Pb-based perovskite solar cell. So far, many efforts have been focused on replacing Pb with Sn. [19,[22][23][24][25][26][27][28][29][30] Some of them were devoted to utilizing Sn to fully replace Pb in the perovskites, [25][26][27][28] and the others were focused on partial Pb-replacement. [19,29,30] However, the performance of the corresponding solar cells based on no matter full or partial Sn-based perovskites was not very good, with maximum PCE lower than 10%, even with a low Sn content of 15%. [19] When the Sn content was increased up to 50%, the highest PCE of the device with a mesoporous structure was 7.27%, [29] and that with a planar structure was just 0.11%. [19] The main reason lies in a poor film quality of Sn-based perovskite.In this work, we have successfully fabricated a 50% Snbased perovskite solar cell with an inverted planar structure of indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene):poly-(styrene sulfonate) (PEDOT:PSS)/CH 3 NH 3 Sn 0.5 Pb 0.5 I 3 /C 60 /2,9dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP)/Ag, where the CH 3 NH 3 Sn 0.5 Pb 0.5 I 3 film was fabricated by a Pb-assisted two step spin-coating method and displayed a compact and uniform morphology. By optimizing the thickness and annealing temperature of the perovskite layer, the highest PCE reached 13.6%, which is, to the best of our knowledge, the most efficient Sn-based perovskite solar cell.In the present work, a Pb-assisted two step method is successfully proposed to fabricate high-quality CH 3 NH 3 Sn 0.5 Pb 0.5 I 3 (MASn 0.5 Pb 0.5 I 3 ) perovskite film on the indium tin oxide (ITO) glass/poly(3,4-ethylenedioxythiophene):poly (styrene sulfonate) (PEDOT:PSS) substrate. The film shows regular crystalline grains with a flat and compact morphology as well as full coverage on the planar PEDOT:PSS substrate. Remarkably, corresponding devices ITO/ PEDOT:PSS/MASn 0.5 Pb 0.5 I 3 /C 60 /2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline/Ag are fabricat...

PSS in inverted planar heterojunction perovskite solar cells.

The feasibility of co-depositing a hole-conductor and a perovskite layer is demonstrated to simplify the preparation process of perovskite solar cells. The CuSCN incorporated in the perovskite layer can participate in forming the perovskite/CuSCN bulk-heterojunction and accelerate hole transport effectively, which eventually leads to a maximum power conversion efficiency of 18.1% with almost no J-V hysteresis.

Organic-inorganic hybrid perovskite solar cells (PSCs) have drawn worldwide intense research in recent years. Herein, we have first applied another p-type inorganic hole-selective contact material, CuS nanoparticles (CuS NPs), in an inverted planar heterojunction (PHJ) perovskite solar cell. The CuS NP-modification of indium tin oxide (ITO) has successfully tuned the surface work function from 4.9 to 5.1 eV but not affect the surface roughness and transmittance, which can effectively reduce the interfacial carrier injection barrier and facilitate high hole extraction efficiency between the perovskite and ITO layers. After optimization, the maximum power conversion efficiency (PCE) has been over 16% with low J-V hysteresis and excellent stability. Therefore, the low-cost solution-processed and stable CuS NPs would be an alternative interfacial modification material for industrial production in perovskite solar cells.

In this work, a CuI anode buffer layer prepared from a facile solution-processed method was introduced in polymer solar cells (PSCs). The CuI films obtained under different spin-coating speeds and anneal treatments, and the performances of corresponding device fabricated with these CuI films were systematically investigated. The results showed that the devices based on CuI anode buffer layer displayed superior performance than conventional devices using poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) sulfonic acid (PEDOT/PSS). The highest power conversion efficiency of the PSCs based on CuI layer reached 4.15% under the illumination of AM 1.5G, 100 mW/cm2. Furthermore, the pristine CuI layer could be applied in PSCs immediately, which shortened the production time of PSCs.

Pt is a classical catalyst that has been extensively used in fuel cell and solar cell electrodes, owing to its high catalytic activity, good conductivity, and stability. In conventional fiber-shaped solar cells, solid Pt wires are usually adopted as the electrode material. Here, we report a Pt nanoparticle-adsorbed carbon nanotube yarn made by solution adsorption and yarn spinning processes, with uniformly dispersed Pt nanoparticles through the porous nanotube network. We have fabricated TiO(2)-based dye-sensitized fiber solar cells with a Pt-nanotube hybrid yarn as counter electrode and achieved a power conversion efficiency of 4.85% under standard illumination (AM1.5, 100 mW/cm(2)), comparable to the same type of fiber cells with a Pt wire electrode (4.23%). Adsorption of Pt nanoparticles within a porous nanotube yarn results in enhanced Pt-electrolyte interfacial area and significantly reduced charge-transfer resistance across the electrolyte interface, compared to a pure nanotube yarn or Pt wire. Our porous Pt-nanotube hybrid yarns have the potential to reduce the use of noble metals, lower the device weight, and improve the solar cell efficiency.