High-mobility, trap-free charge transport in conjugated polymer diodes

• Published in: Nature communications Vol. 10; no. 1; p. 2122
• Main Authors: Nikolka, Mark, Broch, Katharina, Armitage, John, Hanifi, David, Nowack, Peer J., Venkateshvaran, Deepak, Sadhanala, Aditya, Saska, Jan, Mascal, Mark, Jung, Seok-Heon, Lee, Jin‐Kyun, McCulloch, Iain, Salleo, Alberto, Sirringhaus, Henning
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 09.05.2019; Nature Publishing Group; Nature Portfolio
• Subjects: 639/301/923/3931; 639/766/1130/2798; Additives; Bulk density; Carrier density; Charge transport; Crystals; Diodes; Electronics industry; Field effect transistors; Humanities and Social Sciences; Mobility; multidisciplinary; Polymer films; Polymers; Science; Science (multidisciplinary); Semiconductor devices; Single crystals; Small cell lung carcinoma
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-019-10188-y

Charge transport in conjugated polymer semiconductors has traditionally been thought to be limited to a low-mobility regime by pronounced energetic disorder. Much progress has recently been made in advancing carrier mobilities in field-effect transistors through developing low-disorder conjugated polymers. However, in diodes these polymers have to date not shown much improved mobilities, presumably reflecting the fact that in diodes lower carrier concentrations are available to fill up residual tail states in the density of states. Here, we show that the bulk charge transport in low-disorder polymers is limited by water-induced trap states and that their concentration can be dramatically reduced through incorporating small molecular additives into the polymer film. Upon incorporation of the additives we achieve space-charge limited current characteristics that resemble molecular single crystals such as rubrene with high, trap-free SCLC mobilities up to 0.2 cm 2 /Vs and a width of the residual tail state distribution comparable to k B T . Charge transport in organic diodes based on conjugated polymers is severely limited by the high water-related trap concentration and energetic disorder. Here, the authors report high-mobility trap-free charge transport in low-disorder conjugated polymers by incorporating small molecular additives.