Jung, Kwanwook Park, Soohyung Yoo, Jisu Jung, Na Eun Moon, Byung Joon Lee, Sang Hyun Yi, Yeonjin Lee, Hyunbok 2024-01-19T13:00:55Z 2024-01-19T13:00:55Z 2022-01-10 2022-02 0169-4332 https://pubs.kist.re.kr/handle/201004/115803 Recently, the energy cascade structure using multiple light-absorbing layers has been considered as a novel device architecture to overcome the inherent limitations of small-molecule organic photovoltaics (OPVs). The light-absorbing layers in the energy cascade OPVs should have a large overlap between the emission spectrum of a Fo center dot rster resonance energy transfer (FRET) donor and absorption spectrum of a FRET acceptor. An equally important requirement is efficient charge transport across the organic layers by the formation of a suitable energy-level alignment. 5,10,15,20-tetraphenylbisbenz[5,6]indeno[1,2,3-cd:1 ',2 ',3 '-lm]perylene (DBP)/ 5,6,11,12-tetraphenyltetracene (RUB)/5,12-diphenyltetracene (DPT) layers are representative donor systems, which exhibited a high power conversion efficiency in energy cascade OPVs. However, the detailed holetransport mechanism has not been understood. In this study, the energy level alignment of C60/DBP/RUB/ DPT/poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) layers was investigated via in-situ ultraviolet photoelectron spectroscopy and inverse photoelectron spectroscopy. The highest-occupied molecular orbital levels of DBP/RUB/DPT were almost perfectly aligned after their contact, indicating an efficient hole transport toward the anode without hindrance of energy barrier after exciton dissociation. This is owing to the formation of an interface dipole that aligns the charge neutrality levels of the organic layers. English Elsevier BV Elucidation of hole transport mechanism in efficient energy cascade organic photovoltaics using triple donor system Article 10.1016/j.apsusc.2021.151747 1 Applied Surface Science, v.576 Applied Surface Science 576 N scie scopus 000729414000001 2-s2.0-85118830501 Chemistry, Physical Materials Science, Coatings & Films Physics, Applied Physics, Condensed Matter Chemistry Materials Science Physics Article ELECTRONIC-STRUCTURE LEVEL ALIGNMENT EXCITON DIFFUSION PERFORMANCE PSS INTERFACES FILMS Energy cascade Energy level alignment Organic photovoltaics Electronic structure Photoelectron spectroscopy