Lessons learnt from spatially resolved electro- and photoluminescence imaging: Interfacial delamination in CH3NH3PbI3 planar perovskite solar cells upon illumination

© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.The influence of illumination on the long-term performance of planar structured perovskite solar cells (PSCs) is investigated using fast and spatially resolved luminescence imaging. The authors analyze the effect of illuminated current density-voltage (J-V) and light-soaking measurements on pristine PSCs by providing visual evidence for the spatial inhomogeneous evolution of device performance. Regions that are exposed to light initially produce stronger electroluminescence signals than surrounding unilluminated regions, mainly due to a lower contact resistance and, possibly, higher charge collection efficiency. Over a period of several days, however, these initially illuminated regions appear to degrade more quickly despite the device being stored in a dark, moisture- and oxygen-free environment. Using transmission electron microscopy, this accelerated degradation is attributed to delamination between the perovskite and the titanium dioxide (TiO2) layer. An ion migration mechanism is proposed for this delamination process, which is in accordance with previous current-voltage hysteresis observations. These results provide evidence for the intrinsic instability of CH3NH3PbI3-based devices under illumination and have major implications for the design of PSCs from the standpoint of long-term performance and stability

Novel genes from wild barley hordeum spontaneum for barley improvement

Narrowing genetic basis is the bottleneck for modern plant improvement. Genetic variation in wild barley Hordeum spontaneum is much greater than that of either cultivated or landrace H. vulgare gene pool. It represents a valuable but underutilised gene pool for barley improvement as no biological isolation barriers exist between H. spontaneum and cultivated barley. Novel sources of new genes were identified from H. spontaneum for yield, quality, disease resistance and abiotic tolerance. Quantitative trait loci (QTLs) were mapped to all barley chromosomes. A QTL on chromosome 4H from the wild barley consistently increased yield by 7.7% across six test environments. Wild barley H. spontaneum was demonstrated as key genetic resource for drought and salinity tolerance. Two QTLs on chromosomes 2H and 5H increased grain yield by 12–22% under drought conditions. Several QTL clusters were present on chromosomes 1H, 2H, 4H, 6H and 7H from H. spontaneum for drought and salinity tolerance. Numerous candidate genes were identified to associate with tolerance to drought or salinity, and some of the candidate genes co-located with the QTLs for drought tolerance. QTLs/genes for resistance to powdery mildew, leaf rust and scald were mapped to all chromosomes. Scald resistance was found in at least five chromosome locations (1HS, 3H, 6HS, 7HL and 7HS) from H. spontaneum, and simple molecular markers were developed to accelerate transferring of these genes into cultivated barley. Novel beta-amylase allele from H. spontaneum was used to improve barley malting quality. Advanced backcross QTL provides an efficiency approach to transfer novel genes from H. spontaneum to cultivated barley