The combination of donor (D) and acceptor (A) materials in organic solar cells (OSC) determines the corresponding D:A morphology in solar cells and the so-called golden triangle of OSC, that is, cost, power conversion efficiency (PCE), and stability. However, despite the recent advancement in OSC, determining the optimal material combination for industrialization is still a challenge. Herein, we unveil the optimal material combination that exhibits maximum industrial viability. Specifically, the industrial figure of merit (i-FoM) of 7 OSC categories is calculated and further analyzed, including small molecule donor (SMD):fullerene acceptor, SMD:non-fullerene acceptor (NFA), oligomer donor:NFA, terpolymer:NFA, polymer donor:NFA, polymer donor:polymer acceptor, and single-component materials. Since OSC is approaching wide-scale industrialization, our insights into the successes and challenges of these material combinations, particularly their PCE, photostability, and synthetic complexity (SC) index, offer guidance toward accelerating the industrialization of OSC.
This conference presentation was prepared for the Physical Chemistry of Semiconductor Materials and Interfaces XXI conference at SPIE Optics + Photonics 2022.
Here, we report the strategies to increase the photon harvesting in single junction organic photovoltaics by band gap engineering. Low band-gap non-fulllerene small molecule acceptors yield remarkable short-circuit current (26.6 mA/cm2) which comparable to existing high efficiency photovoltaic technologies.
Two π-conjugated acceptor-donor-acceptor-donor-acceptor-type (A-D-A-D-A) oligothiophenes, TT-(2T-DCV-Hex)2 and BT-(2T-DCV-Hex)2 were designed and synthesized with thienothiadiazole (TT) or benzothiadiazole (BT) as the core and dicyanovinyl (DCV) as the terminal acceptor groups for comprehensively investigating and understanding structure–property relationships. The resulting oligomers were first characterized by thermal analysis, UV-Vis spectroscopy, and cyclic voltammetry. By simply changing the BT to TT core in these two oligothiophenes, the highest occupied molecular orbital levels were varied from −5.55 eV for BT-(2T-DCV-Hex)2 to −5.11 eV for TT-(2T-DCV-Hex)2, and the optical band gaps were varied from 1.72 eV for BT-(2T-DCV-Hex)2 to 1.25 eV for TT-(2T-DCV-Hex)2, ascribed to the stronger electron accepting character of the TT core. However, the power conversion efficiency of bulk heterojunction organic solar cells (OSCs) with TT-(2T-DCV-Hex)2 as donor and [6,6]-phenyl C70-butyric acid methyl ester (PC71BM) as acceptor was measured to be 0.04% only, which is much lower than that of BT-(2T-DCV-Hex)2:PC71BM (1.54%). Compared to the TT-(2T-DCV-Hex)2 system, the BT-(2T-DCV-Hex)2 based device shows smoother film surface morphology, and superior charge generation and charge carrier mobilities. Therefore, the results clearly demonstrate that in addition to modifying the alkyl side chains and π-bridge lengths, the design of new small molecules for high-performance OSCs should also aim to choose suitable acceptor units.
KEYWORDS: Optical lithography, Solar energy, Coating, Glasses, Solar cells, Tandem solar cells, Organic photovoltaics, Photovoltaics, Absorption, Optical simulations
The competition in the field of solar energy between Organic Photovoltaics (OPVs) and several Inorganic Photovoltaic technologies is continuously increasing to reach the ultimate purpose of energy supply from inexpensive and easily manufactured solar cell units. Solution-processed printing techniques on flexible substrates attach a tremendous opportunity to the OPVs for the accomplishment of low-cost and large area applications. Furthermore, tandem architectures came to boost up even more OPVs by increasing the photon-harvesting properties of the device. In this work, we demonstrate the road of realizing flexible organic tandem solar modules constructed by a fully roll-to-roll compatible processing. The modules exhibit an efficiency of 5.4% with geometrical fill factors beyond 80% and minimized interconnection-resistance losses. The processing involves low temperature (<70 °C), coating methods compatible with slot die coating and high speed and precision laser patterning.
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