Lin-Long Deng

Low-cost solution-processed copper iodide as an alternative to PEDOT:PSS hole transport layer for efficient and stable inverted planar heterojunction perovskite solar cells

Inverted planar heterojunction (PHJ) perovskite solar cells have attracted great attention due to their advantage of low-temperature fabrication on flexible substrates by solution processing with high efficiency. Poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) is the most widely used hole transport layer (HTL) in inverted PHJ perovskite solar cells; however, the acidic and hygroscopic nature of PEDOT:PSS can cause degradation and reduce the device stability. In this work, we demonstrated that low-cost solution-processed hydrophobic copper iodide (CuI) can serve as a HTL to replace PEDOT:PSS in inverted PHJ perovskite solar cells with high performance and enhanced device stability. A power conversion efficiency (PCE) of 13.58% was achieved by employing CuI as the HTL, slightly exceeding the PEDOT:PSS based device with a PCE of 13.28% under the same experimental conditions. Furthermore, the CuI based devices exhibited better air stability than PEDOT:PSS based devices. The results indicate that low-cost solution-processed CuI is a promising alternative to the PEDOT:PSS HTL and could be widely used in inverted PHJ perovskite solar cells.

Efficient Perovskite Solar Cells Depending on TiO2 Nanorod Arrays.

Perovskite solar cells (PSCs) with TiO2 materials have attracted much attention due to their high photovoltaic performance. Aligned TiO2 nanorods have long been used for potential application in highly efficient perovskite solar cells, but the previously reported efficiencies of perovskite solar cells based on TiO2 nanorod arrays were underrated. Here we show a solvothermal method based on a modified ketone-HCl system with the addition of organic acids suitable for modulation of the TiO2 nanorod array films to fabricate highly efficient perovskite solar cells. Photovoltaic measurements indicated that efficient nanorod-structured perovskite solar cells can be achieved with the length of the nanorods as long as approximately 200 nm. A record efficiency of 18.22% under the reverse scan direction has been optimized by avoiding direct contact between the TiO2 nanorods and the hole transport materials, eliminating the organic residues on the nanorod surfaces using UV-ozone treatment and tuning the nanorod array morphologies through addition of different organic acids in the solvothermal process.

Cerium oxide standing out as an electron transport layer for efficient and stable perovskite solar cells processed at low temperature

In high performance perovskite solar cells (PSCs), the electron transport layer (ETL) has overwhelmingly been dominated by compact titanium oxide (TiO2), which typically requires sintering at around 500 °C. Such a high-temperature sintering procedure prevents TiO2-based PSCs from matching well with plastic substrates and low-cost manufacturing. Here we report cerium oxide (CeOx, x = 1.87), that was prepared facilely through a simple sol–gel method at low temperature (∼150 °C), as an alternative to high-temperature sintering processed TiO2 in the regular architecture of PSCs. With a PCE of 14.32% from the involvement of an optimized CeOx ETL through adjusting the precursor solution, and a higher PCE of 17.04% through introducing a [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) interfacial layer between the CeOx ETL and the perovskite layer, the present work about CeOx-based PSCs renders low-temperature solution-processed CeOx an excellent ETL for high performance perovskite solar cells with improved stability.

Retrieving the Most Prevalent Small Fullerene C56

通讯作者地址: Xie, SY (通讯作者),Xiamen Univ, State Key Lab Phys Chem Solid Surfaces, Coll Chem & Chem Engn, Xiamen 361005, Peoples R China 地址: 1. Xiamen Univ, State Key Lab Phys Chem Solid Surfaces, Coll Chem & Chem Engn, Xiamen 361005, Peoples R China 2. Xiamen Univ, Dept Chem, Coll Chem & Chem Engn, Xiamen 361005, Peoples R China 电子邮件地址: syxie@xmu.edu.cn

Formulation engineering for optimizing ternary electron acceptors exemplified by isomeric PC71BM in planar perovskite solar cells

As the most prevalently used fullerene-based electron acceptor in organic–inorganic solar cells, [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) was isolated into three typical isomers of α-, β1- and β2-PC71BM with comparable molecular orbital energy levels for exemplifying a formulation engineering based on blending the three isomers to improve photovoltaic performance. The power conversion efficiency (PCE), photocurrent hysteresis and stability of planar heterojunction perovskite (CH3NH3PbI3) solar cells have been optimized by formulation engineering with mixed PC71BM (α:β1:β2 = 17:1:2), the specific mixture which represents the best electron acceptor superior to either each of the purified isomers or any other ternary isomers of PC71BM. Microscopic analyses support that molecular aggregation of the isomeric PC71BM was critical to influence the surface morphology and, in turn, the PCE in the range of 0.38–17.56% of the perovskite solar cells involved. This finding about isomer-dependent photovoltaic performance launches a heretofore unknown strategy of formulation engineering for making efficient electron acceptors by mixing various fullerene derivatives having isomeric structures or beyond.

Solution-Processed Cu(In, Ga)(S, Se)2 Nanocrystal as Inorganic Hole-Transporting Material for Efficient and Stable Perovskite Solar Cells

Perovskite solar cells are emerging as one of the most promising candidates for solar energy harvesting. To date, most of the high-performance perovskite solar cells have exclusively employed organic hole-transporting materials (HTMs) such as 2,2′,7,7′-tetrakis-(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene (spiro-OMeTAD) or polytriarylamine (PTAA) which are often expensive and have low hole mobility. Almost all these HTMs reported needed lithium salt, e.g., lithium bis(trifluoromethylsulfonyl)imide (Li-TFSI) doping, to improve hole mobility and performance. However, the use of Li-TFSI should be avoided because the hygroscopic nature of Li-TFSI could cause decomposition of perovskite and reduce device stability. Herein, we employed solution-processed CuIn0.1Ga0.9(S0.9Se0.1)2 (CIGSSe) nanocrystals as a novel inorganic HTM in perovskite solar cells. A power conversion efficiency of 9.15% was obtained for CIGSSe-based devices with improved stability, compared to devices using spiro-OMeTAD as HTM. This work offers a promising candidate of Cu-based inorganic HTM for efficient and stable perovskite solar cells.

Combustion synthesis and electrochemical properties of the small hydrofullerene C50H10.

The hydrofullerene C(50)H(10) is synthesized by low-pressure benzene-oxygen diffusion combustion. The structure of C(50)H(10) is identified through NMR, mass spectrometry, and IR and Raman spectroscopy as a D(5h) symmetric closed-cage molecule with five pairs of fused pentagons stabilized by ten hydrogen atoms. UV/Vis and fluorescence spectrometric analyses disclose its optical properties as comparable with those of its chloride cousin (C(50)Cl(10)). Cyclic and square-wave voltammograms reveal that the first reduction potential of C(50)H(10) is more negative than that of C(50)Cl(10) as well as C(60), with implications for the utilization of C(50)H(10) as a promising electron acceptor for photovoltaic applications.