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Perovskite solar cells (PSCs) with efficiencies greater than 20% have been realized only with expensive organic hole-transporting materials. We demonstrate PSCs that achieve stabilized efficiencies exceeding 20% with copper(I) thiocyanate (CuSCN) as the hole extraction layer. A fast solvent removal method enabled the creation of compact, highly conformal CuSCN layers that facilitate rapid carrier extraction and collection. The PSCs showed high thermal stability under long-term heating, although their operational stability was poor. This instability originated from potential-induced degradation of the CuSCN/Au contact. The addition of a conductive reduced graphene oxide spacer layer between CuSCN and gold allowed PSCs to retain >95% of their initial efficiency after aging at a maximum power point for 1000 hours under full solar intensity at 60°C. Under both continuous full-sun illumination and thermal stress, CuSCN-based devices surpassed the stability of spiro-OMeTAD–based PSCs. [ABSTRACT FROM AUTHOR]

The surge of the power conversion efficiency of metal halide lead perovskite solar cells comes with concerns, such as the long-term ecotoxicity of lead compounds, their sensitivity toward moisture and oxygen, or the scarcity of some of their components. Most perovskite solar cells still suffer from serious stability problems when measured under real working conditions (maximum power point tracking at 60°C). In the long run, stability will certainly decide on the fate of CH3NH3PbI3 and related lead perovskites for their use in photovoltaic modules. Herein, we show an effective and inexpensive strategy to perform ageing of perovskite solar cells under maximum power point tracking. For the first time, we analyze the issue of power extraction from solar cells exhibiting hysteresis. We show that a standard tracking algorithm such as perturb and observe fails to converge to the maximum power point of the solar cell if it exhibits j( V) hysteresis, and we present an effective strategy to stabilize the algorithm. We show that enforcing oscillations in forward bias can boost the mean power output of some perovskite solar cells by more than 10%, in contrast to a reference crystalline silicon solar cell. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In the past few years, organic-inorganic halide perovskites have rapidly emerged as promising materials for photovoltaic applications, but simultaneously achieving high performance and long-term stability has proved challenging. Here, we show a one-step solution-processing strategy using phosphonic acid ammonium additives that results in efficient perovskite solar cells with enhanced stability. We modify the surface of methylammonium lead triiodide (CH3NH3PbI3) perovskite by spin-coating its precursor solution in the presence of butylphosphonic acid 4-ammonium chloride. Morphological, structural and elemental analyses show that the phosphonic acid ammonium additive acts as a crosslink between neighbouring grains in the perovskite structure, through strong hydrogen bonding of the -PO(OH)2 and -NH3+ terminal groups to the perovskite surface. The additives facilitate the incorporation of the perovskite within a mesoporous TiO2 scaffold, as well as the growth of a uniform perovskite layer at the surface, enhancing the material's photovoltaic performance from 8.8 to 16.7% as well as its resistance to moisture. [ABSTRACT FROM AUTHOR]

A low band gap quinolizino acridine based molecule was designed and synthesized as new hole transporting material for organic-inorganic hybrid lead halide perovskite solar cells. The functionalized quinolizino acridine compound showed an effective hole mobility in the same range of the state-of-the-art spiro-MeOTAD and an appropriate oxidation potential of 5.23 eV vs the vacuum level. The device based on this new hole transporting material achieved high power conversion efficiency of 12.8% under the illumination of 98.8 mW cm-2, which was better than the well-known spiro- MeOTAD under the same conditions. Moreover, this molecule could work alone without any additives, thus making it to be a promising candidate for solid-state photovoltaic application. [ABSTRACT FROM AUTHOR]