Tzung-Han Lai
University of Florida
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Publication
Featured researches published by Tzung-Han Lai.
Advanced Materials | 2014
Song Chen; Sai-Wing Tsang; Tzung-Han Lai; John R. Reynolds; Franky So
The VOC loss in several polymer-fullerene solar cells is determined. Based on these data, a major source of photovoltage loss is attributed to the low dielectric constants of the polymers. Such loss is close to zero if the dielectric constant of the polymer-fullerene blend is close to 5.
ACS Applied Materials & Interfaces | 2015
Iordania Constantinou; Tzung-Han Lai; Dewei Zhao; Erik Klump; James J. Deininger; Chi Kin Lo; John R. Reynolds; Franky So
The effect of air processing, with air exposure varying from minutes to hours prior to encapsulation, on photovoltaic device performance has been studied through a series of electrical characterizations and optical simulations for a donor/acceptor polymer-based organic solar cell based on poly(dithienogermole-alt-thienopyrrolodione) p(DTG-TPD)/PC71BM blends. A ∼10% degradation in power conversion efficiency was observed due to air processing with 10 min exposure time, with AM1.5 power conversion efficiencies (PCEs) decreasing from 8.5 ± 0.25% for devices processed in inert nitrogen atmosphere to 7.7 ± 0.18% for devices processed in ambient air. After 3 h air exposure, the PCE leveled off at 7.04 ± 0.1%. This decrease is attributed partially to interface issues caused by exposure of the electrode materials to oxygen and water and partially to a degradation of the hole transport in the active layer.
Scientific Reports | 2015
Do-Young Kim; Tzung-Han Lai; Jae Woong Lee; Jesse R. Manders; Franky So
Commercially available near-infrared (IR) imagers are fabricated by integrating expensive epitaxial grown III-V compound semiconductor sensors with Si-based readout integrated circuits (ROIC) by indium bump bonding which significantly increases the fabrication costs of these image sensors. Furthermore, these typical III-V compound semiconductors are not sensitive to the visible region and thus cannot be used for multi-spectral (visible to near-IR) sensing. Here, a low cost infrared (IR) imaging camera is demonstrated with a commercially available digital single-lens reflex (DSLR) camera and an IR sensitive organic light emitting diode (IR-OLED). With an IR-OLED, IR images at a wavelength of 1.2 µm are directly converted to visible images which are then recorded in a Si-CMOS DSLR camera. This multi-spectral imaging system is capable of capturing images at wavelengths in the near-infrared as well as visible regions.
ACS Applied Materials & Interfaces | 2015
Iordania Constantinou; Tzung-Han Lai; Erik Klump; Subhadip Goswami; Kirk S. Schanze; Franky So
The effect of polymer side chains on device performance was investigated for PBDT(EtHex)-TPD(Oct):PC70BM and PBDT(EtHex)-TPD(EtHex):PC70BM BHJ solar cells. Going from a linear side chain on the polymers acceptor moiety to a branched side chain was determined to have a negative impact on the overall device efficiency, because of significantly reduced short-circuit current (J(sc)) and fill factor (FF) values. Sub-bandgap external quantum efficiency (EQE) and transient photoluminescence (PL) measurements showed more-efficient carrier generation for the polymer with linear side chains, because of a higher degree of charge-transfer (CT) state delocalization, leading to more-efficient exciton dissociation. Furthermore, the increase in π-π stacking distance and disorder for the bulkier ethylhexyl side chain were shown to result in a lower hole mobility, a higher bimolecular recombination, and a higher energetic disorder. The use of linear side chains on the polymers acceptor moiety was shown to promote photogeneration, because of more-effective CT states and favorable carrier transport resulting in improved solar cell performance.
Nature Photonics | 2012
Cephas E. Small; Song Chen; Jegadesan Subbiah; Chad M. Amb; Sai-Wing Tsang; Tzung-Han Lai; John R. Reynolds; Franky So
Advanced Functional Materials | 2013
Jesse R. Manders; Sai-Wing Tsang; Michael J. Hartel; Tzung-Han Lai; Song Chen; Chad M. Amb; John R. Reynolds; Franky So
Advanced Energy Materials | 2012
Song Chen; Cephas E. Small; Chad M. Amb; Jegadesan Subbiah; Tzung-Han Lai; Sai-Wing Tsang; Jesse R. Manders; John R. Reynolds; Franky So
Materials Today | 2013
Tzung-Han Lai; Sai-Wing Tsang; Jesse R. Manders; Song Chen; Franky So
Advanced Functional Materials | 2014
Jesse R. Manders; Tzung-Han Lai; Yanbin An; Weikai Xu; Jae Woong Lee; Do-Young Kim; Gijs Bosman; Franky So
Macromolecules | 2016
Caroline Grand; Sujin Baek; Tzung-Han Lai; Nabankur Deb; Wojciech Zajaczkowski; Romain Stalder; Klaus Müllen; Wojciech Pisula; David G. Bucknall; Franky So; John R. Reynolds