\chapter*{INTRODUCTION}
\addcontentsline{toc}{chapter}{INTRODUCTION}





While a direct link of computer to the brain is desired and is slowly developed \cite{DeMarse2005,Martins2019,Pais-Vieira2013},.........


\begin{figure}[ht]\centering
	\centering\includegraphics[width=10cm]{figures_PDF/gens.pdf}
	\caption{Principle schemes of different generations of OLED devices.} \label{fig:OLED_gen}
\end{figure}



\pdfbookmark[1]{Aim and novelty}{sec:obj}
\section*{Aim and novelty}



While TADF emitters are one of the heavily researched branch of organic semiconductors some effects like ......

To achieve this aim several tasks were set:

\begin{itemize}
    \item Utilize time-resolved spectra measurements to perform in-depth analysis of thermally assisted delayed fluorescence in differently modified compounds containing pyrimidine acceptor and carbazole, phenothiazine or phenoxazine donor moieties.
  
    \item Investigate solid-state TADF emission and decay transients of molecules possessing different core rigidity, yet similar photophysical properties in dilute solutions, to assess effects of conformational disorder.
    
    % Elucidate
    \item Reveal the origin of fast dual delayed fluorescence in compounds were donor and acceptor moieties are bound by non-conjugated \textsigma{}-bridge and evaluate their performance as TADF emitters.
    
    \item Assess how small modifications of phenyl-pyrimidine acceptor core with methyl groups or linking pattern of carbazole donor units affect TADF emission properties and decay lifetimes.
    
    
    
\end{itemize}


%\newpage
\pdfbookmark[1]{Statements to be defended}{sec:statements}
\section*{Statements to be defended}
%\addcontentsline{toc}{chapter}{Statements to be defended}

\begin{enumerate}[1.]
	\item Some of the undesirable solid-state conformational disorder effects in donor-acceptor TADF compounds can be prevented  by
    designing a rigid molecular core or accelerating reverse intersystem crossing rate.
	
	
	\item TADF donor--acceptor molecules with hyperconjugated spacer (D--σ--A) should be designed with great care as weak coupling between donor and acceptor results in extremely low radiative decay rate which can hardly compete with various non-radiative decay pathways. 
	
\end{enumerate}


\section*{Layout of the dissertation}
%\pdfbookmark[1]{Layout of the dissertation}{SEC:layout}
\label{SEC:layout}
The dissertation is presented as a collection of articles with chapters 1--3 summarizing the findings in papers [\textbf{A1--A6}]. The papers are numbered in chronological order of their publish date.

% \citepapernumFIVE{EmWL}{Minimiz}{PXAPYR}{DeepBlue}{Cbz}

In the first chapter based on papers \citepapernumTWO{EmWL}{Minimiz}  the effects of conformational disorder in solid-state are explored in several TADF compounds exhibiting similar emissions, but possessing different molecular structure.
In the second chapter, based on \citepapernumONE{Sigma} the in--depth property analysis of donor--acceptor compounds joined by hyperconjugated \textsigma{} bridge is presented. Here several donor units were bound to triazine acceptor fragment by hexafluoroisopropylidene spacer unit.  Though initial investigation of the compounds suggested extremely fast TADF lifetime, the time-resolved analysis revealed interplay of intra-/intermolecular charge transfer states with exceptionally long prompt fluorescence.
In the final chapter based on articles \citepapernumTHREE{PXAPYR}{DeepBlue}{Cbz}......


\section*{Contribution of the author}

\label{SEC:contrib}

 The author performed all photophysical characterization, steady-state and time-resolved spectroscopy experiments, processed and analysed the obtained data. 
 The author also contributed to preparation and participated in discussions of all manuscripts.




