\usepackage{tkz-euclide}

\begin{figure}[h]
\begin{tikzpicture}
   \tkzInit[xmax=6,ymax=7,xmin=0,ymin=0]
   \draw [thick, ->] (0,0) -- (0,6) node[text=cyan,anchor=south]{Preis};
   \draw [thick, ->] (0,0) -- (7,0) node[text=cyan,anchor=west]{Nachgefragte Menge};
   \draw [thin] (0,5) -- (5,0);
   \draw [thin] (-0.1,2) node[text=cyan,anchor=east] {$p2$}-- (3,2);
   \draw [thin] (-0.1,3) node[text=cyan,anchor=east] {$p1$}-- (2,3);
   \draw [thin] (2,3) -- (2,2);
   \draw [draw=cyan,thin, ->] (-0.4,2.7) -- (-0.4,2.3);
   \fill[draw=black,fill=cyan] (0,5) -- (2,3) -- (0,3);
   \fill[draw=black,fill=red] (2,3) -- (3,2) -- (2,2);
   \fill[draw=black,fill=green] (0,3) -- (2,3) -- (2,2) -- (0,2);
   \draw [thick, ->] (1.5,4.5) node[anchor=south west] {Konsumentenrente} -- (0.75,3.75);
   \draw [thick, ->] (2.5,3.5) node[anchor=south west] {Zusätzliche Rente der vorherigen Nachfrager} -- (1.5,2.5);
   \draw [thick, ->] (2.75,2.75) node[anchor=south west] {Rente neuer Nachfrager} -- (2.25,2.25);
  \end{tikzpicture}
\end{figure}