Erik Klump
University of Florida
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Publication
Featured researches published by Erik Klump.
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.
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.
Advanced Materials | 2018
Bhoj Gautam; Erik Klump; Xueping Yi; Iordania Constantinou; Nathan T. Shewmon; Amin Salehi; Chi Kin Lo; Zilong Zheng; Jean-Luc Brédas; Kenan Gundogdu; John R. Reynolds; Franky So
Interfaces between donor and acceptor in a polymer solar cell play a crucial role in exciton dissociation and charge photogeneration. While the importance of charge transfer (CT) excitons for free carrier generation is intensively studied, the effect of blending on the nature of the polymer excitons in relation to the blend nanomorphology remains largely unexplored. In this work, electroabsorption (EA) spectroscopy is used to study the excited-state polarizability of polymer excitons in several polymer:fullerene blend systems, and it is found that excited-state polarizability of polymer excitons in the blends is a strong function of blend nanomorphology. The increase in excited-state polarizability with decreased domain size indicates that intermixing of states at the interface between the donor polymers and fullerene increases the exciton delocalization, resulting in an increase in exciton dissociation efficiency. This conclusion is further supported by transient absorption spectroscopy and time-resolved photoluminescence measurements, along with the results from time-dependent density functional theory calculations. These findings indicate that polymer excited-state polarizability is a key parameter for efficient free carrier generation and should be considered in the design and development of high-performance polymer solar cells.
Advanced electronic materials | 2015
Iordania Constantinou; Tzung-Han Lai; Hsien-Yi Hsu; Sin-Hang Cheung; Erik Klump; Kirk S. Schanze; S. K. So; Franky So
Advanced Energy Materials | 2017
Iordania Constantinou; Xueping Yi; Nathan T. Shewmon; Erik Klump; Cheng Peng; Sofia Garakyaraghi; Chi Kin Lo; John R. Reynolds; Felix N. Castellano; Franky So
Chemistry of Materials | 2016
Tzung-Han Lai; Iordania Constantinou; Caroline Grand; Erik Klump; Sujin Baek; Hsien-Yi Hsu; Sai-Wing Tsang; Kirk S. Schanze; John R. Reynolds; Franky So
ACS Applied Materials & Interfaces | 2016
Nathan T. Shewmon; Hyeonggeun Yu; Iordania Constantinou; Erik Klump; Franky So
Advanced Energy Materials | 2016
Bhoj Gautam; Robert Younts; Wentao Li; Liang Yan; Evgeny O. Danilov; Erik Klump; Iordania Constantinou; Franky So; Wei You; Harald Ade; Kenan Gundogdu
Chemistry of Materials | 2017
Qianqian Zhang; Liang Yan; Xuechen Jiao; Zhengxing Peng; Shubin Liu; Jeromy James Rech; Erik Klump; Harald Ade; Franky So; Wei You
Organic Electronics | 2017
Erik Klump; Iordania Constantinou; Tzung-Han Lai; Franky So