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In this work, we present an extensive characterization of plasma-assisted atomic-layer-deposited SnO2layers, with the aim of identifying key material properties of SnO2to serve as an efficient electron transport layer in perovskite solar cells (PSCs). Electrically resistive SnO2films are fabricated at 50 °C, while a SnO2film with a low electrical resistivity of 1.8 × 10–3Ω cm, a carrier density of 9.6 × 1019cm–3, and a high mobility of 36.0 cm2/V s is deposited at 200 °C. Ultraviolet photoelectron spectroscopy indicates a conduction band offset of ∼0.69 eV at the 50 °C SnO2/Cs0.05(MA0.17FA0.83)0.95Pb(I2.7Br0.3) interface. In contrast, a negligible conduction band offset is found between the 200 °C SnO2and the perovskite. Surprisingly, comparable initial power conversion efficiencies (PCEs) of 17.5 and 17.8% are demonstrated for the champion cells using 15 nm thick SnO2deposited at 50 and 200 °C, respectively. The latter gains in fill factor but loses in open-circuit voltage. Markedly, PSCs using the 200 °C compact SnO2retain their initial performance at the maximum power point over 16 h under continuous one-sun illumination in inert atmosphere. Instead, the cell with the 50 °C SnO2shows a decrease in PCE of approximately 50%.

Abstract

This work is part of the interlaboratory collaboration to study the stability of organic solar cells containing PCDTBT polymer as a donor material. The varieties of the OPV devices with different device architectures, electrode materials, encapsulation, and device dimensions were prepared by seven research laboratories. Sets of identical devices were aged according to four different protocols: shelf lifetime, laboratory weathering under simulated illumination at ambient temperature, laboratory weathering under simulated illumination, and elevated temperature (65 °C) and daylight outdoor weathering under sunlight. The results generated in this study allow us to outline several general conclusions related to PCDTBT-based bulk heterojunction (BHJ) solar cells. The results herein reported can be considered as practical guidance for the realization of stabilization approaches in BHJ solar cells containing PCDTBT.

Nanostructured polymer‐based solar cells (PSCs) have emerged as a promising low‐cost alternative to conventional inorganic photovoltaic devices and are now a subject of intensive research both in academia and industry. For PSCs to become practical efficient devices, several issues should still be addressed, including further understanding of their operation and stability, which in turn are largely determined by the morphological organisation in the photoactive layer. The latter is typically a few hundred nanometres thick film and is a blend composed of two materials: the bulk heterojunction consisting of the electron donor and the electron acceptor. The main requirements for the morphology of efficient photoactive layers are nanoscale phase segregation for a high donor/acceptor interface area and hence efficient exciton dissociation, short and continuous percolation pathways of both components leading through the layer thickness to the corresponding electrodes for efficient charge transport and collection, and high crystallinity of both donor and acceptor materials for high charge mobility. In this paper, we review recent progress of our understanding on how the efficiency of a bulk heterojunction PSC largely depends on the local nanoscale volume organisation of the photoactive layer.

Poly[2‐methoxy‐5‐(3,7‐dimethyloctyloxy)‐1,4‐phenylenevinylene] (MDMO‐PPV) blended with poly[oxa‐1,4‐phenylene‐1,2‐(1‐cyanovinylene)‐2‐methoxy,5‐(3,7‐dimethyloctyloxy)‐1,4‐phenylene‐1,2‐(2‐cyanovinylene)‐1,4‐phenylene] (PCNEPV) has been used as the active layer for an all‐polymer photovoltaic cell. The photovoltaic performance of devices is improved by a thermal treatment, which alters the morphology of the active layer. The morphology of the MDMO‐PPV/PCNEPV blend has been studied with conventional transmission electron microscopy and energy‐filtered transmission electron microscopy based on electron energy loss spectroscopy. The nitrogen of the cyano group within the PCNEPV has been be detected, and two‐dimensional nitrogen distribution maps have been acquired. Nitrogen‐rich domains have a size of approximately 20–50 nm and are homogeneously distributed over the entire film. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1001–1007, 2005

In order to achieve the highest performance of organometal trihalide perovskite solar cells, it is required to recognize the dominant mechanisms which play a key role in a perovskite material. In the following studies, we have focused on the interfacial recombination between the hole transporting layer (HTL) and the perovskite CH3NH3PbI3in solar cell devices with p–i–n architecture. It has been shown that Cu:NiOxused as HTL drastically decreases a short–circuit photocurrent (Jsc) and an open–circuit voltage (Voc). However, we have found that an addition of PTAA thin layer improves cells quality and, as a consequence, the efficiency of such solar cells increases by 2%. Here, we explain both Jscand Voclosses with a theory of the “dead layer” of perovskite material where a very high surface recombination occurs. We demonstrate the numerical and experimental studies by the means of series detailed analyses to get in–depth understanding of the physical processes behind it. Using a drift–diffusion model, it is shown that the presence of a parasitic recombination layer influences mostly the current distribution in the simulated samples explaining Jscand Voclosses. The following results could be useful for improving the quality of perovskite solar cells.