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Solution-processed nonvolatile organic transistor memory devices are fabricated by employing semiconductor blends of p-channel 6,13-bis­(triisopropylsilylethynyl)­pentacene and n-channel poly­{[N,N′-bis­(2-octyldodecyl)-naphthalene-1,4,5,8-bis­(dicarboximide)-2,6-diyl]-alt-5,5′-(2,2′-bithiophene)} (P­(NDI2OD-2T); N2200) on polystyrene-brush as a polymer electret. Electret-based memory characteristics are significantly changed depending on the frontier molecular orbitals of the active semiconductors because the charge-trapping efficiency is mainly determined by the energy barrier to transfer electrons and holes from the active channel to the electret layer. A semiconductor mixture with an optimized blending ratio results in an efficient programming and erasing process. Thus, we obtained a remarkably high ratio of ON/OFF current (memory ratio) about 107 and a large amount of shifts in the threshold voltage (memory window) between the programmed and erased states of 55 V, while single-component N2200 showed only writing-once-read-many (WORM)-type memory. Especially, the programmed data can be stably retained more than 10 years with a sufficient memory ratio of 103. Furthermore, our semiconductor blend system leads to preferable vertical phase separation, which affords good reliability under a sequential memory operation condition as well as stability in ambient air. It is expected that our memory devices can be applied for versatile data storage in printed and flexible electronic applications.

The purpose of this article is to describe passage effects on Dynamic Indicators of Basic Early Literacy Skills-Next Edition Oral Reading Fluency (DIBELS Next ORF) progress-monitoring measures for Grades 1 through 6. Approximately 572 students per grade (total N with at least one data point = 3,092) read all three DIBELS Next winter benchmark passages in the prescribed order, and within 2 weeks read four additional progress-monitoring passages in a randomly assigned and counterbalanced order. All 20 progress-monitoring passages were read by students in Grades 1 through 4; 16 passages were read in Grade 5 and 12 passages were read in Grade 6. Results focus on the persistence of form effects in spite of a priori criteria used in passage development. The authors describe the utility of three types of equating methods (i.e., mean, linear, and equipercentile equating) in ameliorating these effects. Their conclusions focus on preferred equating methods with small samples, the impact of form effects on progress-monitoring decision making, and recommendations for future use of ORF passages for progress monitoring.

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