The molecular structure of the hole transporting material (HTM) play an important role in hole extraction in a perovskite solar cells. It has a significant influence on the molecular planarity, ...energy level, and charge transport properties. Understanding the relationship between the chemical structure of the HTM's and perovskite solar cells (PSCs) performance is crucial for the continued development of the efficient organic charge transporting materials. Using molecular engineering approach we have constructed a series of the hole transporting materials with strategically placed aliphatic substituents to investigate the relationship between the chemical structure of the HTMs and the photovoltaic performance. PSCs employing the investigated HTMs demonstrate power conversion efficiency values in the range of 9% to 16.8% highlighting the importance of the optimal molecular structure. An inappropriately placed side group could compromise the device performance. Due to the ease of synthesis and moieties employed in its construction, it offers a wide range of possible structural modifications. This class of molecules has a great potential for structural optimization in order to realize simple and efficient small molecule based HTMs for perovskite solar cells application.
Novel nonspiro, fluorene‐based, small‐molecule hole transporting materials (HTMs) V1050 and V1061 are designed and synthesized using a facile three‐step synthetic route. The synthesized compounds ...exhibit amorphous nature with a high glass transition temperature, a good solubility, and decent thermal stability. The planar perovskite solar cells (PSCs) employing V1050 generated an excellent power conversion efficiency of 18.3%, which is comparable to 18.9% obtained with the state‐of‐the‐art Spiro‐OMeTAD. Importantly, the devices based on V1050 and V1061 show better stability compared to devices based on Spiro‐OMeTAD when aged without any encapsulation under uncontrolled humidity conditions (relative humidity around 60%) in the dark and under continuous full sun illumination.
Novel, non‐spiro, amorphous hole‐transporting materials (HTMs) (V1050 and V1061) with fluorene fragments are synthesized using a facile three‐step synthetic route. Planar perovskite solar cells with the V1050 HTM exhibited an excellent power conversion efficiency (PCE) of 18.3%. Furthermore, V1050‐ and V1061‐based devices show better stability compared to devices based on Spiro‐OMeTAD.
The search for new classes of hole transporting materials (HTMs) is a very important task on the way towards commercialization of perovskite solar cells (PSCs). In this work, the synthesis and ...performance in PSCs of new enamine-based HTMs are presented. The synthesis scheme is very short, consisting of only one step, starting from commercially available aromatic amines. Moreover, the reaction does not require metal catalysts and is based on condensation chemistry with water as a by-product. It was shown that PSCs with such materials reach high power conversion efficiencies (PCE), with the highest PCE of 19% achieved for the V1021 -based device. This work establishes enamines as a very promising class of materials for application in PSCs.
Five new star‐shaped carbazole‐based molecules are successfully synthesized from low‐cost, commercially available reagents via a simple one‐step synthesis route. All carbazole derivatives comprise a ...3,6‐diaminocarbazole core with carbazole peripheral groups substituted at the 2‐ or 3‐positions and various aliphatic side chains. These molecules are evaluated as hole transporting materials to replace 2,2′,7,7′‐tetrakis‐(N,N‐di‐p‐methoxyphenylamine)‐9,9′‐spirobifluorene (spiro‐OMeTAD) in perovskite solar cells. Power conversion efficiencies of the devices with these carbazole hole transporting layers reach 19.0%, comparable with 19.7% obtained with the spiro‐OMeTAD‐based device. The thermal and operational stability of the candidate molecules are found to depend on the side chain substituents. Two candidate molecules with ethyl side chains show superior thermal stability compared with that of the reference solar cells prepared with spiro‐OMeTAD.
New starburst molecules, bearing the carbazole moiety both as a central core and as peripheral groups, are synthesized and evaluated as hole transporting materials for perovskite solar cells. Their power conversion efficiencies range from 16.3% to 19.0%. Compounds bearing short aliphatic chains show exceptionally high glass transition temperatures, resulting in superior thermal stability compared with that of spiro‐OMeTAD.
Stabilizing the high‐performing perovskite solar cells (PSCs) with low‐cost and simply affordable hole‐transporting materials (HTMs) has been identified as an ongoing ambitious challenge. Herein, a ...series of enamine‐based HTMs having different central heteroatoms (C, N, O, and S) and a number of enamine branches is designed and synthesized. The impact of varied central heteroatom cores is investigated in‐depth including thermal, photophysical, and photovoltaic properties. Importantly, molecularly engineered HTMs are obtained by a single condensation reaction without the need for expensive catalysts, inert reaction conditions, or tedious product purification. PSCs with a power conversion efficiency (PCE) of over 20% can be realized with the triphenylamine core HTM (V1435), a result comparable with spiro‐OMeTAD. HTMs based on tetraphenylmethane (V1431) and diphenyl sulfide (V1434) cores give a slightly lower performance under similar device fabrication conditions. This work demonstrates how rational molecular engineering of a simple condensation approach can produce HTMs for high‐performing PSCs without sacrificing the PCE.
Engineering of the central heteroatom in the chemical structure of enamine hole‐transporting materials is presented, leading to the one‐pot‐synthesized low‐cost hole‐transporting material V1435 based on a nitrogen‐containing triphenylamine central core to reach a power conversion efficiency of over 20% in perovskite solar cells, which is on par with reference spiro‐OMeTAD.
D-π-A architecture metal-free organic dyes, with a tetrahydroquinoline unit as electron donor, were designed and synthesized for solid-state dye-sensitized solar cells. The sensitizer series was ...designed to develop a structure–property relationship. These dyes are obtained from relatively cheap starting materials, without the use of expensive catalysts, rigorously anhydrous or oxygen-free conditions. The highest solid-state device conversion efficiency (η) 3.3% (JSC = −5.9 mA cm−2, VOC = 780 mV) and fill factor FF = 0.72 under 100 mW cm−2 (AM 1.5G) solar irradiation was achieved with dye D4 employing a hydrazone fragment as the spacer between the donor 3-alkoxy-1-phenyl-1,2,3,4-tetrahydroquinoline and the rhodanine acceptor of the sensitizer.
•Organic dyes for ssDSSCs, with tetrahydro-quinoline fragment have been synthesized.•Dyes are obtained using cheap starting materials and simple synthetic procedures.•Solid-state dye sensitized solar cells have been constructed.•The best overall conversion efficiency of solid-state device was 3.3%.
A new cross-linkable monomer containing 1,3-diphenylethenylcarbazolyl-based hole-transporting moieties and four reactive epoxy groups, was prepared by a multistep synthesis route from ...1,3-bis(2,2-diphenylethenyl)-9H-carbazol-2-ol and its application for the in situ formation of cross-linked hole transporting layers was investigated. A high concentration of flexible aliphatic epoxy chains ensures good solubility and makes this compound an attractive cross-linking agent. The synthesized compounds were characterized by various techniques, including differential scanning calorimetry, xerographic time of flight, and electron photoemission in air methods.
In a short period of time, the rapid development of perovskite solar cells attracted a lot of attention in the science community with the record for power conversion efficiency being broken every ...year. Despite the fast progress in power conversion efficiency there are still many issues that need to be solved before starting large scale commercial applications, such as, among others, the difficult and costly synthesis and usage of toxic solvents for the deposition of hole transport materials (HTMs). We herein report new enamine-based charge transport materials obtained
via
a simple one step synthesis procedure, from commercially available precursors and without the use of expensive organometallic catalysts. The developed materials demonstrated rapid loss of mass during thermogravimetry analysis suggesting that they could be processed not only using solution processing but also
via
vacuum deposition. Furthermore, all HTMs demonstrated high charge carrier mobility with
H2
possessing the highest mobility of 2.5 × 10
−2
cm
2
V
−1
s
−1
under strong electric fields. The investigated materials were employed in vacuum-deposited p-i-n perovskite solar cells and champion devices with enamine
H2
demonstrate a PCE of 18.4%.
New sublimable enamine-based charge transport materials, obtained
via
a simple one step synthesis, are used in efficient fully vacuum deposited perovskite solar cells.
Synthesis of 1,3-diphenylethenylcarbazolyl-based charge transporting materials involving electron donating hydrazone moieties and an electron withdrawing 1,3-indandione moiety is reported. The ...obtained materials were examined by various techniques, including differential scanning calorimetry, UV-Vis spectroscopy, xerographic time of flight technique and the electron photoemission in air method. Photoemission spectra of the amorphous films of the investigated compounds showed ionization potentials of 5.54-5.90 eV. The hole drift mobility was measured by the xerographic time of flight technique. The highest hole drift mobility, exceeding 10(-5) cm(2)/V · s at 6.4 × 10(5) V/cm electric field, was observed for the 1,3-diphenylethenylcarbazolyl derivative molecularly doped with a N,N-diphenylhydrazone moiety in the polymeric host bisphenol-Z polycarbonate (PC-Z).
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