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Rationally managing the secondary‐phase excess lead iodide (PbI2) in hybrid perovskite is of significance for pursuing high performance perovskite solar cells (PSCs), while the challenge remains on its conversion to a homogeneous layer that is robust stable against environmental stimuli. We herein demonstrate an effective strategy of surface reconstruction that converts the excess PbI2 into a gradient lead sulfate‐silica bi‐layer, which substantially stabilizes the perovskite film and reduces interfacial charge transfer barrier in the PSCs device. The perovskite films with such bi‐layer could bear harsh conditions such as soaking in water, light illumination at 70 % relative humidity, and the damp‐thermal (85 °C and 30 % humidity) environment. The resulted PSCs deliver a champion efficiency up to 24.09 %, as well as remarkable environmental stability, e.g. retaining 78 % of their initial efficiency after 5500 h of shelf storage, and 82 % after 1000 h of operational stability testing. [ABSTRACT FROM AUTHOR]

CsPbI2Br perovskite solar cells have achieved rapid development owing to their exceptional optoelectronic properties and relatively outstanding stability. However, open‐circuit voltage (Voc) loss caused by band mismatch and charge recombination between perovskite and charge transporting layer is one of the crucial obstacles to further improve the device performance. Here, we proposed a bilayer electron transport layer ZnO(bottom)/SnO2(top) to reduce the Voc loss (Eloss) and promote device Voc by ZnO insert layer thickness modulation, which could improve the efficiency of charge carrier extraction/transfer and suppress the charge carrier recombination. In addition, guanidinium iodide top surface treatment is used to further reduce the trap density, stabilize the perovskite film and align the energy levels, which promotes the fill factor, short‐circuit current density (Jsc), and stability of the device. As a result, the champion cell of double‐side optimized CsPbI2Br perovskite solar cells exhibits an extraordinary efficiency of 16.25% with the best Voc as high as 1.27 V and excellent thermal and storage stability. [ABSTRACT FROM AUTHOR]

Modulating the n- and p-type interfacial charge transport properties of the metal–semiconductor interface is vital to realizing high performance two-dimensional material nanodevices and is still a significant challenge. Here, a boron nitride (BN)-graphene lateral heterostructure (LH) was used as the interfacial tunneling layer to control the Schottky barrier, Fermi level pinning and charge injection efficiency of the metal–MoS2 interface. The BN-graphene LH with graphene-N junction structure decreased the n-type vertical Schottky barrier and enhanced the interfacial tunneling probability, while the graphene-B junction structure decreased the p-type vertical Schottky barrier. Consequently, the n-type Au/LH–MoS2 interface with Ohmic character and high tunneling probability (∼0.242) and the p-type vertical Schottky barrier of about 0.20 eV for the Pt/LH–MoS2 interface were achieved. Compared to other reported BN or graphene tunneling layers, such a BN-graphene LH tunneling layer not only suppressed the charge scattering from the metal electrode to the MoS2 layer and the Fermi level pinning effect, but also reduced the contact resistance between metal electrode and tunneling layer. The underlying mechanisms were revealed to be due to the charge transfer, orbitals and interfacial dipole. This work improves the current understanding of the metal–MoS2 interface and proposes a new way to overcome the current severe contact issues for future nanoelectronic and optoelectronic applications. [ABSTRACT FROM AUTHOR]

All‐inorganic perovskite CsPbI2Br have been regarded as a promising candidate to tackle the thermal instability issue of organic–inorganic perovskite solar cells. However, the serious interfacial charge recombination and large voltage potential loss in cells circumscribe their performance and commercialization. Herein, a facile approach is demonstrated in which the SnO2 electron transport layer is modified with short‐period deep‐ultraviolet (DUV) photoactivation process to decrease the work function and achieve better energy alignment with the conduction band of perovskites. Such modification triggers efficient charge transfer and reduces the charge recombination. Moreover, first‐principles calculation further demonstrates that DUV‐treated SnO2 can strengthen the interface interaction, reduce the interface stress caused by lattice mismatch, induce more ordered perovskite structure, enlarge transfer charge from 0.71 to 2.33 e, gain larger built‐in field (from 0.74 to 2.09 eV), lower work function, and smaller conduction band offset. Thus, all‐inorganic CsPbI2Br solar cells based on DUV‐treated SnO2 exhibit a significant enhancement in power conversion efficiency, and the champion cell achieves an elevated efficiency of 15.1% with a superior Voc of 1.22 V and better stability. [ABSTRACT FROM AUTHOR]

ABSTRACT A pyromellitic diimide building block, 2,6- bis(2-decyltetradecyl)−4,8-di(thiophen-2-yl)pyrrolo[3,4- f]isoindole-1,3,5,7(2H,6H)-tetraone ( 4), is synthesized. Based on this building block and other electron-rich units such as 2,2′-bithiophene, thieno[3,2- b]thiophene and 4,8- bis(dodecyloxy)benzo[1,2- b:4,5- b′]dithiophene, three conjugated polymers P1, P2, and P3 are prepared in good yield via Stille coupling polymerization. These new copolymers have good solubility in common organic solvents and exhibit good thermal stability. The optical, electrochemical, and thermal properties of these polymers P1-P3 are carefully investigated, and their applications in solution-processed organic field-effect transistors are also studied. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2454-2464 [ABSTRACT FROM AUTHOR]

The charge transport layer is crucial to the performance and stability of the perovskite solar cells (PSCs). Compared with other conventional metal oxide electron transport materials, SnO2 has a deeper conduction band and higher electron mobility, and can efficiently serve as an electron transport layer to facilitate charge extraction and transfer. Herein, an optimized low‐temperature solution‐processed SnO2 electron transport layer is achieved by doping polyethylenimine polyelectrolyte into SnO2 for the first time in the PSCs. It is found that the performance of all aspects of the doped SnO2 film is improved over that of the pristine SnO2 film. The better energy level alignment, larger built‐in field, enhanced electron transfer/extraction, and reduced charge recombination all contribute to the improved device performance. Finally, a PSC with a power conversion efficiency of 20.61% is successfully prepared under low temperature below 150 °C. Moreover, the stability of the doped SnO2‐based device is also greatly improved. [ABSTRACT FROM AUTHOR]

Interface engineering is of critical importance to achieve high performance perovskite solar cells. Herein, a readily-prepared and sustainable hole transport layer (HTL) based on the poly(3,4-ethylenedioxy-thiophene):sulfonated acetone-formaldehyde (PEDEO:SAF) as an alternative of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is reported to efficiently improve the film electrical properties, enhance the charge transfer and extraction, and finally enhance the efficiency and stability of inverted perovskite solar cells. Compared with PEDOT:PSS HTL, PEDOT:SAF HTL possesses higher film conductivity, and less acidity, leading to much improved ambient stability of devices. This work suggests that PEDOT:SAF HTL could be an efficient HTL for high performance and stable perovskite solar cells. Image 1 • The perovskite solar cell efficiency was enhanced by using PEDOT:SAF hole transport layer. • Higher film conductivity and less acidity were contributed to the performance and stability improvement. • The charge transfer and extraction process was enhanced by using PEDOT:SAF hole transport layer. [ABSTRACT FROM AUTHOR]