Platinum(II)-bis(aryleneethynylene) complexes for solution-processible molecular bulk heterojunction solar cells

Area of Science:

• Organometallic Chemistry
• Materials Science
• Photovoltaics

Background:

• Organic solar cells offer a promising avenue for renewable energy generation.
• Developing efficient and solution-processible electron-donor materials is crucial for advancing organic photovoltaics (OPVs).
• Small-molecule organic semiconductors provide tunable electronic properties and simplified fabrication.

Purpose of the Study:

• To synthesize and characterize novel solution-processible platinum(II)-bis(aryleneethynylene) complexes.
• To investigate the impact of varying electron-donor groups (triphenylamine, thiophene) on the optoelectronic and photovoltaic properties of these complexes.
• To evaluate the performance of these complexes as electron-donor materials in bulk heterojunction (BHJ) solar cells.

Main Methods:

• Chemical synthesis of four new platinum(II) complexes.
• Physicochemical characterization (spectroscopy, electrochemistry).
• Computational studies (time-dependent density functional theory - TD-DFT).
• Fabrication and testing of BHJ solar cells using the synthesized complexes blended with a fullerene acceptor ([6,6]-phenyl-C(71)-butyric acid methyl ester - PC70BM).
• Measurement of device performance (power conversion efficiency, open-circuit voltage, short-circuit current density, fill factor).
• Analysis of charge transport properties (hole mobility) in spin-coated thin films.

Main Results:

• Successful synthesis and characterization of four novel platinum(II)-bis(aryleneethynylene) complexes.
• Optical and TD-DFT studies indicated that stronger electron-donor groups enhance solar absorption.
• The complexes functioned effectively as electron donors in BHJ solar cells when paired with PC70BM.
• The best performing solar cell achieved a power conversion efficiency of 2.37%, with an open-circuit voltage of 0.83 V, short-circuit current density of 7.10 mA cm(-2), and fill factor of 0.40.
• Thin films exhibited p-channel field-effect charge transport with hole mobilities up to 2.4×10(-4) cm(2) V(-1) s(-1).

Conclusions:

• The developed platinum(II) complexes are suitable for solution-processed BHJ solar cells.
• Tuning electron-donor groups in these organometallic complexes significantly influences their optoelectronic properties and solar cell performance.
• These findings highlight the potential of well-defined organometallic complexes as light-harvesting materials for efficient organic photovoltaics.