Search results for "energy conversion efficiency"
showing 10 items of 102 documents
Dithienopyrrolobenzothiadiazole-based organic dyes for efficient dye-sensitized solar cells
2014
Four novel D–π–A metal-free organic dyes DTP1–4 containing a dithienopyrrolobenzothiadiazole (DTPBT) unit were synthesized and applied in dye-sensitized solar cells, where DTPBT was employed as a π-spacer for the first time. The photophysical, electrochemical and photovoltaic properties of the dyes were systematically investigated. The dyes DTP1–4 showed broad absorption spectra and high molar extinction coefficient, resulting in high light harvesting efficiency. In addition, the impacts of donors and the thiophene unit as an additional π-spacer were also studied. The results showed that the dye DTP4 with triphenylamine as the donor exhibited better photovoltaic performance than DTP1–3 with…
Anti-recombination organic dyes containing dendritic triphenylamine moieties for high open-circuit voltage of DSSCs
2013
Abstract Three novel sensitizers with dendritic triphenylamine moieties were synthesized and used for dye-sensitized solar cells (DSSCs). Their absorption spectra, electrochemical and photovoltaic properties were extensively investigated. All three DSSCs exhibit high open-circuit voltage over 0.8 V. The photovoltaic results indicate that the dendritic triphenylamine units improve the open-circuit voltage, which is attributed to the retardation of charge recombination, demonstrating that non-planar and larger molecules exert better blocking function. Under standard global AM 1.5 solar conditions, the best performance of the DSSCs exhibits a short-circuit current density of 10.35 mA cm−2, an …
Electronic Band Transitions in γ-Ge3N4
2021
This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 and 2019-2020 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission. Support from Estonian Research Council grant PUT PRG 619 is gratefully acknowledged. The multi-anvil experiments at LMV were supported by the French Government Laboratory of Excellence initiative no ANR-10-LABX-0006, the Région Auvergne and the European Regional Development Fund (ClerVolc Contribution Number 478).
Boosting inverted perovskite solar cell performance by using 9,9-bis(4-diphenylaminophenyl)fluorene functionalized with triphenylamine as a dopant-fr…
2019
In this study, two newly developed small molecules based on 9,9-bis(4-diphenylaminophenyl)fluorene functionalized with triphenylamine moieties, namely TPA-2,7-FLTPA-TPA and TPA-3,6-FLTPA-TPA, are designed, synthesized and characterized. The electrochemical, optical and thermal properties of both materials are investigated using various techniques. Afterwards, these materials are employed as dopant-free hole transporting materials (HTMs) in planar inverted perovskite solar cell devices with the aim of determining the device performance and studying their stability in comparison with reference N4,N4,N4′′,N4′′-tetra([1,10-biphenyl]-4-yl)-[1,1′:4′,1′′-terphenyl]-4,4′′-diamine (TaTm)-based devic…
Double D–π–A branched dyes – a new class of metal-free organic dyes for efficient dye-sensitized solar cells
2017
Double branched donor acceptor compounds (D–π–A)2L, whose separate branches are linked by saturated chains or ring systems, are highly promising sensitizers for dye-sensitized solar cells (DSSCs). Their photovoltaic performance η (power conversion efficiency PCE) is higher than the η value of the corresponding single branched sensitizers D–π–A. This advantage can be attributed to the lower aggregation tendency and to the higher loading density of the chromophores on the semi-conductor surface (TiO2). Moreover, the intramolecular transfer of the excitation energy can enhance the contact time of the adsorbed dye molecules in the excited state S1 and thus reduce the unwanted charge recombinati…
High voltage vacuum-deposited CH3NH3PbI3-CH3NH3PbI3 tandem solar cells
2018
The recent success of perovskite solar cells is based on two solid pillars: the rapid progress of their power conversion efficiency and their flexibility in terms of optoelectrical properties and processing methods. That versatility makes these devices ideal candidates for multi-junction photovoltaics. We report an optically optimized double junction CH3NH3PbI3–CH3NH3PbI3 tandem solar cell where the matched short-circuit current is maximized while parasitic absorption is minimized. The use of an additive vacuum-deposition protocol allows us to reproduce calculated stack designs, which comprise several charge selective materials that ensure appropriate band alignment and charge recombination…
Vacuum deposited perovskite solar cells employing dopant-free triazatruxene as the hole transport material
2017
Abstract Planar perovskite solar cells using organic charge selective contacts were fabricated. In a vacuum deposited perovskite-based solar cell, dopant and additive free triazatruxene as the hole transport layer was introduced for device fabrication. High open-circuit voltage of 1090 mV was obtained using methylammonium lead iodide (Eg=1.55 eV) as light harvesting material, thus representing a loss of only 460 mV which is in close vicinity of mature silicon technology (400 mV). The devices showed a very competitive photovoltaic performance, monochromatic incident photon-to-electron conversion efficiency of 80% and the power conversion efficiencies in excess of 15% were measured with a neg…
Fullerene imposed high open-circuit voltage in efficient perovskite based solar cells
2016
Five different commercially available fullerenes are evaluated as hole blocking/electron transporting materials in p–i–n methylammonium lead iodide perovskite solar cells using a vacuum deposited perovskite absorber layer. A significant enhancement of the solar cell performance can be obtained by selecting a suitable fullerene derivative. Open-circuit voltages as high as 1.11 volts are obtained leading to a power conversion efficiency of 14.6%.
Enhanced power-conversion efficiency in organic solar cells incorporating copolymeric phase-separation modulators
2018
A new class of copolymers containing oligothiophene moieties with different lengths and fullerene units have been designed and prepared by an easy and inexpensive one-step synthetic approach. The incorporation of small quantities of these copolymers into bulk heterojunction (BHJ) solar cells with donor regioregular polythiophene (P3HT) and an acceptor fullerene derivate (PCBM) results in good control of the phase separation process without further affecting the BHJ optoelectronic properties. Indeed, under thermal annealing these copolymers allow the modulation of the growth of domains whose size depends on the length of the copolymer repetitive units. Domain size on the same length scale as…
Phenothiazine dye featuring encapsulated insulated molecular wire as auxiliary donor for high photovoltage of dye-sensitized solar cells by suppressi…
2019
Abstract Two efficient dye-sensitized solar cells have been fabricated by two novel D–D–π–A phenothiazine-based organic dyes (PH2 and PH3) with an encapsulated insulated molecular wire (EIMW) as an auxiliary donor. The cell sensitized by PH2 with EIMW as an auxiliary donor shows a much higher photovoltage (Voc) relative to the reference dye PH1 without EIMW, because the former dye can inhibit dye aggregation and suppress the charge recombination effectively. The results show that the cell sensitized by PH2 with co-adsorption of chenodeoxycholic acid obtains a high power conversion efficiency, even higher than that of the cell based on N719. Thus, an effective way to increase the photovoltag…