Press Room

Solving an Organic Semiconductor Mystery

Friday, January 16th 2015

Naomi Ginsberg, a faculty chemist with the Physical Biosciences and Materials Sciences Divisions and the University of California Berkeley, led a team that used a unique form of microscopy to study the domain interfaces within an especially high-performing solution-processed organic semiconductor called TIPS-pentacene. She and her team discovered a cluttered jumble of randomly oriented nanocrystallites that become kinetically trapped in the interfaces during solution casting. Like debris on a highway, these nanocrystallites impede the flow of charge-carriers. Organic semiconductors are prized for light emitting diodes (LEDs), field effect transistors (FETs) and photovoltaic cells. As they can be printed from solution, they provide a highly scalable, cost-effective alternative to silicon-based devices. Uneven performances, however, have been a persistent problem. Scientists have known that the performance issues originate in the domain interfaces within organic semiconductor thin films, but have not known the cause.

This mystery now appears to have been solved with the help of transient absorption (TA) microscopy, a technique in which femtosecond laser pulses excite transient energy states and detectors measure the changes in the absorption spectra. The Berkeley researchers carried out TA microscopy on an optical microscope they constructed themselves that enabled them to generate focal volumes that are a thousand times smaller than is typical for conventional TA microscopes. They also deployed  multiple different light polarizations that allowed them to isolate interface signals not seen in either of the adjacent domains. The methology developed by Ginsberg and her team to uncover structural motifs at hidden interfaces in organic semiconductor thin films should add a predictive factor to scalable and affordable solution-processing of these materials. In addition to minimizing discontinuities and maximizing charge-carrier mobility, their technique would replace the trial-and-error approach typically taken by researchers.

Berkeley Lab’s 2014 Highlights

Monday, January 5th 2015

Take a tour of the science, people, and events that shaped our year on an interactive timeline. Several of these contributions came from the Physical Biosciences Division, including a study that produced the first detailed look at the 3D structure of the Cas9 enzyme and how it partners with guide RNA, a breakthrough discovery of how living cells process and respond to chemical information, and the identification of microbial genes that can improve both the tolerance and the production of biogasoline in engineered strains of E. coli. There is something on this timeline for everyone! As you take a journey in 2014, start dreaming about what is possible in 2015.

Berkeley Innovators Elected to National Academy of Inventors

Thursday, December 18th 2014

Biochemist Jennifer Doudna and chemical engineer Jay Keasling were among 170 new fellows recognized for outstanding contributions to innovation in patents and licensing, innovative discovery and technology, significant impact on society, and support and enhancement of innovation. Doudna, PBD faculty biochemist and professor of molecular and cell biology at UC Berkeley, co-invented a precision DNA editing technique that has revolutionized genetic research and gene therapy. Called CRISPR/Cas9, it is already the basis of several startups, including Caribou Biosciences Inc., co-founded by Doudna. Keasling, a pioneer in synthetic biology, is associate laboratory director for Biosciences and CEO of the Joint BioEnergy Institute in Emeryville. His inventions resulted in engineered microbes to produce the world’s first low-cost antimalarial drug. He has co-founded 4 companies, including Amyris Biotechnologies, the company that optimized the modified biosynthetic process for producing artemisinic acid, the basis for the drug.

CellScope, Inc., Co-Founder Shares Her Experiences in Developing New Home Product

Wednesday, December 17th 2014

A recent New York Times series on Women in Tech features Amy Sheng, co-founder of CellScope, Inc., a company that was spun out of the laboratory of PBD Deputy for Science, Daniel Fletcher. In January, CellScope, Inc., is releasing the Oto HOMETM in California, a cell phone attachment that includes an otoscope to allow parents to take a video of a child’s middle ear that can be sent to the doctor for diagnosis of infection. In this video and blog story, Sheng shares the inspiration for this product and describes the development process. Sheng’s experiences underscore her belief that it is important to have more female scientists and engineers designing products to bring the results of their perspectives to the marketplace. Learn more about the myriad applications of this technology that turns the camera of a mobile phone or tablet computer into a high-quality light microscope.