Organic Semiconductors, Lead Halide Perovskites, and Quantum Dots: Interface Engineering of Multi-Component, Solution-Processible Semiconductors for Optoelectronic Device Applications

Conley, Ashley, Chemical Engineering - School of Engineering and Applied Science, University of Virginia
Giri, Gaurav, EN-Chem Engr Dept, University of Virginia
Choi, Joshua, EN-Chem Engr Dept, University of Virginia

Semiconductors are ubiquitous in modern life, existing as transistors in electronics, light emitting diodes in visual displays, and solar cells on houses and company rooftops. Scientists continue to push the limits of material properties to ameliorate the most technologically challenging problems facing humanity, such as climate change, the breakdown of Moore’s law, and the continued need for affordable, widely-available technology for our expanding population. At the heart of semiconductor technology is the necessity to deeply understand and control material-dependent structure-property relationships. However, single-component materials can have trade-offs or intrinsic limitations that hinder further advancement. But with a plethora of semiconductors available, increasingly-clever design of multi-component, hybrid materials with complementary properties have proven instrumental in overcoming intrinsic limitations of single-phase materials.
In this work, we utilize organic semiconductors, three-dimensional perovskites, two-dimensional perovskites, and quantum dots to exploit their unique properties to enhance structure-property relationships. In this work, we first combine organic semiconductors with two-dimensional perovskites, and second, we incorporate quantum dot dopants in three-dimensional perovskites. In the first pairing, we leveraged the structural tunability of two-dimensional perovskites to finely control the crystal structure of a small molecule organic semiconductor, 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene), whose propensity to adopt multiple molecular packing motifs with highly-contrasting optoelectronic properties has been an ongoing challenge. Next, we studied singlet fission, an exciton multiplication process with applications in organic photovoltaics, of the perovskite-templated TIPS-pentacene structures to show that a key exciton separation process is enhanced by a factor greater than two when molecular packing structural disorder is reduced. Finally, modeling of TIPS-pentacene/perovskite interfacial structures revealed that perovskite surfaces allow for closer packing of TIPS-pentacene molecules. In the second pairing, we doped three-dimensional perovskite with lead sulfide quantum dots to utilize the outstanding charge carrier mobility of three-dimensional perovskites with the quantum-confined, narrow band emission of the quantum dots for its application as scintillation X-ray detectors. We show that the light yield, a key performance metric for scintillators, of quantum-dot-doped perovskites is substantially improved compared to that reported for single-phase perovskites. These works motivate the interface engineering of hybrid semiconductor material systems to control structural-optoelectronic properties.

PHD (Doctor of Philosophy)
molecular packing, singlet fission, lead halide perovskites, scintillators, interface engineering
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