By Eray S. Aydil
New York University, Tandon School of Engineering
Department of Chemical and Biomolecular Engineering
Pyrite FeS2, (fool’s gold) has long been considered an ideal semiconductor for low-cost, sustainable solar cells because it is composed of earth-abundant, non-toxic, inexpensive elements and it absorbs light so strongly that a 100 nm thick film can absorb >90 % of incoming sunlight. Pyrite was pursued vigorously in the 1980’s for thin film solar cells but all attempts failed, with disappointing efficiencies, less than 3 %. With the rise of other high efficiency thin film solar cells, such as CdTe and CuInGaSe2 (CIGS), enthusiasm for pyrite vanished. Fool’s gold was dead as a solar cell material. Interest in FeS2 reemerged around 2009 motivated in part by the sustainability, cost, and toxicity concerns with CdTe and CIGS. This time, however, a few groups, including ours, are pursuing the fundamental origins of the disappointing performance of FeS2 rather than attempting to produce efficient cells via the trial-and-error approach that previously failed. For three decades, electronic transport data from thin FeS2 films were interpreted as p-type, while single crystals have been unambiguously established as n-type. This unexpected difference came to be known as the “Doping Puzzle”. Recently, we resolved this puzzle and showed that FeS2 films are not p-type but in fact n-type. In thin films with low mobility hopping conduction artificially inverts Hall coefficient, incorrectly indicating p-type conduction. For three decades, FeS2 based solar cells might in fact have been designed based on a mistaken presumption. In this talk I will summarize our recent efforts in reviving FeS2 as a photovoltaic material.
Eray S. Aydil is the Alstadt Lord Mark Professor at NYU. Previously he was the Ronald L. and Janet A. Christenson Chair in Renewable Energy and Executive Officer of the Department of Chemical Engineering and Materials Science at the University of Minnesota. He is a Fellow of the AVS and Editor-in-Chief of the Journal of Vacuum Science and Technology. He received B.S. in chemical engineering and in materials science, both from U. C. Berkeley in 1986, and Ph.D. in chemical engineering in from the Univ. of Houston in 1991. He was a postdoc at Bell Labs until 1993 and then professor and vice chair in the chemical engineering department at U.C. Santa Barbara (UCSB) until 2005. In 2005, he joined the Department of Chemical Engineering and Materials Science (CEMS) at the Univ. of Minnesota where he remained until 2018. In 2018 he moved to NYU. In recognition of his research, he has received the Peter Mark Award and the Plasma Prize from the AVS, the Norman Hackerman Young Author Award of ECS, the NSF National Young Investigator Award, and the Camille-Dreyfus Teacher-Scholar Award. He has received the Professor of the year award at UCSB thrice and most recently the Horace T. Morse-Univ. of Minnesota Alumni Association Award for Outstanding Contributions to Graduate and Professional Education in 2017.
For more information, contact Vanessa Irizarry at [email protected]