Substitution effects on the photoinduced excited state dynamics of perylenemonoimides in solution and thin films.

Perylene monoimide (PMI) derivatives are attracting significant attention due to their strong absorption in the visible range, thermal stability, and synthetic accessibility. These properties make them promising for application in various areas such as optoelectronic devices, photosensitizers, In this work, the photophysical properties and excited state dynamics of four different PMI derivatives (PMIB, BrPMITB, PMITB, and APITB) were studied in solution and thin films utilizing steady-state and time-resolved spectroscopic techniques. Among the four PMI derivatives, APITB is designed as a donor-acceptor dyad, with thianthrene as a donor and PMI as an acceptor.

Theoretical study of electronic sum frequency generation spectroscopy to assess the buried interfaces.

This article provides a comprehensive theoretical background of electronic sum frequency generation (ESFG), a second-order nonlinear spectroscopy technique. ESFG is utilized to investigate both exposed and buried interfaces, which are challenging to study using conventional spectroscopic methods. By overlapping two incident beams at the interface, ESFG generates a beam at the sum of their frequencies, allowing for the extraction of valuable interfacial molecular information such as molecular orientation and density of states present at interfaces.

Development of electronic sum frequency generation spectrophotometer to assess the buried interfaces.

The interfacial region between two bulk media in organic semiconductor based devices, such as organic field-effect transistors (OFETs), organic light-emitting diodes, and organic photovoltaics, refers to the region where two different materials such as an organic material and an electrode come in contact with each other. Although the interfacial region contains a significantly smaller fraction of molecules compared to the bulk, it is the primary site where many photoinduced excited state processes occur, such as charge transfer, charge recombination, separation, energy transfer processes, etc. All such photoinduced processes have a dependence on molecular orientation and density of states at the interfaces, therefore having an understanding of the interfacial region is essential.

Probing the excited state dynamics in perinone molecules for photovoltaic applications using transient absorption spectroscopy.

Nonfullerene polyaromatic molecules such as perinone are emerging as alternatives to fullerene derivatives due to their low manufacturing cost, ease of functionalization, and processing to improve the efficiency of optoelectronic devices. In this paper, we have used ultrafast transient absorption (TA) spectroscopy to probe the excited state dynamics in and perinone molecules. We have performed TA measurements in solution as well as thin films to provide a comprehensive understanding of excited-state processes occurring in and perinone molecules.