The high performance of the perovskite solar cells (PSCs) cannot be achieved without a layer of efficient hole-transporting materials (HTMs) to retard the charge recombination and transport the photogenerated hole to the counterelectrode. Herein, we report the use of boryl oxasmaragdyrins (SM01, SM09, and SM13), a family of aromatic core-modified expanded porphyrins, as efficient hole-transporting materials (HTMs) for perovskite solar cells (PSCs). These oxasmaragdyrins demonstrated complementary absorption spectra in the low-energy region, good redox reversibility, good thermal stability, suitable energy levels with CHNHPbI perovskite, and high hole mobility. A remarkable power conversion efficiency of 16.5% (V = 1.09 V, J = 20.9 mA cm, fill factor (FF) = 72%) is achieved using SM09 on the optimized PSCs device employing a planar structure, which is close to that of the state-of-the-art hole-transporting materials (HTMs), spiro-OMeTAD of 18.2% (V = 1.07 V, J = 22.9 mA cm, FF = 74%). In contrast, a poor photovoltaic performance of PSCs using SM01 is observed due to the interactions of terminal carboxylic acid functional group with CHNHPbI.
Cobalt(II) porphyrins bearing ortho/para‐amino and ortho‐nitro groups at meso‐phenyl rings have been prepared and employed for catalytic hydrogen generation. Electrochemical and catalytic studies show that position and electronic nature of the substituents strongly affect catalytic activity and overpotential of catalysis. Our study reveals that the complex with ortho‐aminophenyl substituents on porphyrin core displays higher activity toward H2 evolution with rate constant of 1.1 ×
105 M−1 s−1 at onset potential close to thermodynamic reduction potential of trifluoroacetic acid (TFA), and 89% efficiency. On the other hand, the reactions involving cobalt porphyrins with para‐aminophenyl or ortho‐nitrophenyl groups showed lower or no activity under the same experimental conditions, implying the significant role of pendant ortho‐amino groups in accelerating the intramolecular proton transfer and the proton‐hydride interactions to thermodynamically favor H2 evolution.
A major challenge toward commercialization of perovskite solar
cells (PSCs) is the development of cost-effective hole-transport materials
(HTMs) with good hole mobility and long-term stability. Porphyrinoids
such as metal-free oxasmaragdyrins as alternative HTMs in PSCs show
promising power conversion at lower costs. In this study, a difluoroboryl
oxasmaragdyrin, SM09, has been modified by introducing alkoxy chains
with different chain lengths (methoxy (OMe), ethoxy (OEt), butoxy
(OBu), and octyloxy (OOct)) at the central core position, affecting
molecular packing, varying intermolecular distances, and consequently
altering the hole mobility. These modified oxasmaragdyrins were used
as HTMs for the planar PSCs. The device performance was evaluated
and correlated with the alkyl chain length and was rationalized by
photophysical characterizations. The device efficiencies decrease
with an increase in the alkyl chain length from the highest PCE of
15.47% for SM-OMe to 13.35% for SM-OOct. The best performance was
obtained in SM-OMe, due to its higher hole mobility (3.75 × 10–4 cm2 V–1 s–1) and stronger p-type character. In the future, a simple tuning of
alkyl chain length at central core positions of oxasmaragdyrin HTMs
can be an effective strategy to enhance the power conversion efficiency
(PCE) of PSCs.
All-inorganic perovskite CsPbIBr 2 offers both an optimal bandgap and good stability. The perovskite solar cells (PSCs) with CsPbIBr 2 as a solar harvester utilize mainly spiro-OMeTAD as a hole-transporting material (HTM). Still, these PSCs are prone to degradation and not cost-effective. Herein we examined, for the first time, a metal-free dimethoxyboranyl (B(OR) 2 ) chelated oxasmaragdyrin, SM-OMe, as an alternative bifunctional HTM for CsPbIBr 2 -based PSCs to demonstrate promising power conversion efficiencies at lower costs.The devices with SM-OMe as HTM outperform spiro-OMeTAD-based devices with the highest power conversion efficiency of 6.04%. This enhanced performance can be attributed to an HTM and sensitizer dual-function of SM-OMe, which extends the absorption edge and consequently improves the short circuit current density. Furthermore, SM-OMe-based devices exhibited better charge extracting and hole-transporting properties. Hence, this study demonstrates an effective and successful utilization of a new HTM with a bifunctional role as an alternative to conventional spiro-OMeTAD in all-inorganic PSCs.
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