Lim, Hunhee Kim, Donghun Choi, Min-Jae Sargent, Edward H. Jung, Yeon Sik Kim, Jin Young 2024-01-19T18:34:13Z 2024-01-19T18:34:13Z 2021-09-04 2019-12 1614-6832 https://pubs.kist.re.kr/handle/201004/119299 Quantum-dot (QD) photovoltaics (PVs) offer promise as energy-conversion devices; however, their open-circuit-voltage (V-OC) deficit is excessively large. Previous work has identified factors related to the QD active layer that contribute to V-OC loss, including sub-bandgap trap states and polydispersity in QD films. This work focuses instead on layer interfaces, and reveals a critical source of V-OC loss: electron leakage at the QD/hole-transport layer (HTL) interface. Although large-bandgap organic materials in HTL are potentially suited to minimizing leakage current, dipoles that form at an organic/metal interface impede control over optimal band alignments. To overcome the challenge, a bilayer HTL configuration, which consists of semiconducting alpha-sexithiophene (alpha-6T) and metallic poly(3,4-ethylenedioxythiphene) polystyrene sulfonate (PEDOT:PSS), is introduced. The introduction of the PEDOT:PSS layer between alpha-6T and Au electrode suppresses the formation of undesired interfacial dipoles and a Schottky barrier for holes, and the bilayer HTL provides a high electron barrier of 1.35 eV. Using bilayer HTLs enhances the V-OC by 74 mV without compromising the J(SC) compared to conventional MoO3 control devices, leading to a best power conversion efficiency of 9.2% (>40% improvement relative to relevant controls). Wider applicability of the bilayer strategy is demonstrated by a similar structure based on shallow lowest-unoccupied-molecular-orbital (LUMO) levels. English WILEY-V C H VERLAG GMBH Suppressing Interfacial Dipoles to Minimize Open-Circuit Voltage Loss in Quantum Dot Photovoltaics Article 10.1002/aenm.201901938 1 ADVANCED ENERGY MATERIALS, v.9, no.48 ADVANCED ENERGY MATERIALS 9 48 N scie scopus 000493157200001 2-s2.0-85074603899 Chemistry, Physical Energy & Fuels Materials Science, Multidisciplinary Physics, Applied Physics, Condensed Matter Chemistry Energy & Fuels Materials Science Physics Article ENERGY-LEVEL ALIGNMENT SUB-BANDGAP STATES THIN-FILMS HOLE-EXTRACTION SOLAR-CELLS CARRIER MOBILITY CHARGE-TRANSPORT METAL-OXIDE EFFICIENT POLYMER band engineering hole transport layers interfacial dipole quantum dot solar cells