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Key Tradeoffs Limiting the Performance of Organic Photovoltaics
Author(s) -
Ramirez Ivan,
Causa' Martina,
Zhong Yufei,
Banerji Natalie,
Riede Moritz
Publication year - 2018
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201703551
Subject(s) - organic solar cell , limiting , photovoltaics , materials science , fullerene , energy conversion efficiency , nanotechnology , open circuit voltage , voltage , optoelectronics , photovoltaic system , engineering physics , electrical engineering , physics , polymer , mechanical engineering , engineering , composite material , quantum mechanics
2017 saw the publication of several new material systems that challenge the long‐held notion that a driving force is necessary for efficient exciton dissociation in organic photovoltaics (OPVs) and that a loss of ≈0.6 eV between the energy of the charge transfer state E ct and the energy corresponding to open circuit is general. In light of these developments, the authors combine insights from device physics and spectroscopy to review the two key tradeoffs limiting OPV performances. These are the tradeoff between the charge carrier generation efficiency and the achievable open circuit voltage ( V oc ) and the tradeoff between device thickness (light absorption) and fill factor. The emergence of several competitive nonfullerene acceptors (NFAs) is exciting for both of these. The authors analyze what makes these materials compare favorably to fullerenes, including the potential role of molecular vibrations, and discuss both design criteria for new molecules and the achievable power conversion efficiencies.