Lead sulfide colloidal quantum dot photodiodes (PbS QDPDs) exhibit a high energy conversion efficiency for infrared detection. Despite the high photoinduced current, the performance of PbS QDPDs is limited by the high dark current which is rarely investigated. Understanding the dark current in PbS QDPDs is critical to improving the detectivity of PbS QDPDs. Herein, it is demonstrated that minority carriers of I‐passivated PbS films and trap sites of EDT‐passivated PbS films are related to the dark current of PbS QDPD. Utilizing annealing and low‐temperature ligand exchange processes, the dark current density can be decreased almost tenfold by suppressing the minority carrier diffusion in the PN junction and trap‐assisted charge injection from the electrode. PN junction simulation, space charge limited current measurements, as well as structural, optical, and chemical characterizations are conducted to elucidate the origins of the dark current suppression. The authors achieve the lowest dark current density of 2.9 × 10−5 mA cm−2 at −1 V among PbS‐based QDPDs and a high detectivity of 6.7 × 1012 Jones at 980 nm. It is believed that this work provides fundamental understanding of carrier statistics in nanomaterials and device performance as well as a technological basis for realizing low‐cost high‐performance optoelectronic devices.

Perovskite has been actively studied for optoelectronic applications, such as photodetectors and light-emitting diodes (LEDs), because of its excellent optoelectronic properties. However, ionic bonds of the perovskite structure are vulnerable to chemicals, which makes perovskite incompatible with photolithography processes that use polar solvents. Such incompatibility with photolithography hinders perovskite patterning and device integration. Here, an all-solution based cesium lead halide perovskite (Cs x Pb y Br z ) patterning method is introduced in which PbBr 2 is patterned and then synthesized into Cs x Pb y Br z . Each step of the top-down patterning process (e.g., developing, etching, and rinsing) is designed to be compatible with existing photolithography equipment. Structural, chemical, and optical analyses show that the PbBr 2 pattern of (10 µm) 2 squares is successfully transformed into CsPbBr 3 and Cs 4 PbBr 6 with excellent absorption and emission properties. Highresolution photoconductor arrays and luminescent pattern arrays are fabricated with CsPbBr 3 and Cs 4 PbBr 6 on various substrates, including flexible plastic films, to demonstrate their potential applications in image sensors or displays. The research provides a fundamental understanding of the properties and growth of perovskite and promotes technological advancement by preventing degradation during the photolithography process, enabling the integration of perovskite arrays into image sensors and displays.

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Qin, Y., Kabir, M. A., Wang, H. W., Lee, Y. H., Hong, S. H., Kim, J. Y., Yook, M. J., Kim, D. S., Kim, C. S., Kwon, H. and Kim, W. 2013. Assessment of genetic diversity and relationships based on RAPD and AFLP analyses in Miscanthus genera landraces. Can. J. Plant Sci. 93: 171–182. In this study, molecular markers, random amplified polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP) as well as combined RAPD and AFLP analysis were used to assess genetic diversity in a reference set of 38 Miscanthus accessions of which 32 were collected from South Korea and 6 from foreign countries. Using 30 selected RAPD primers, 197 amplified products were generated with an average of 6.6 bands, of which 135 bands were polymorphic (68.6%). A total of 1150 bands were detected by four-primer AFLP combinations with an average of 287.5 bands, out of which 923 bands were polymorphic (80.3%) across all the accessions. Analysis of molecular variance (AMOVA) indicated that a high proportion of the genetic variation (56% for RAPD and 58% for AFLP) was found among the Miscanthus species in South Korea. Genetic relationship was estimated using the Jaccard's coefficient values between different accessions, ranging from 0.23 to 0.93 in RAPD and 0.34 to 0.94 in AFLP. The un-weighted pair group method with arithmetic mean (UPGMA) analysis demonstrated less difference between RAPD and AFLP when alternative similarity coefficient was applied. The principal coordinates (PCO) analysis also revealed the significant geographic structure in the tested accessions. Among the accessions, SNU-M-040, 074 and 157 were highly divergent. Pattern of isolation by distance was observed in Miscanthus accessions, indicating that significant genetic differentiation among accessions might be due to the geographic distance.