In Situ Visualization and Quantification of Electrical Self‐Heating in Conjugated Polymer Diodes Using Raman Spectroscopy

Abstract

AbstractSelf‐heating in organic electronics can lead to anomalous electrical performance and even accelerated degradation. However, in the case of disordered organic semiconductors, self‐heating effects are difficult to quantify using electrical techniques alone due to complex transport properties. Therefore, more direct methods are needed to monitor the impact of self‐heating on device performance. Here, self‐heating in poly[2,6‐(4,4‐bis‐(2‐ethylhexyl)‐4H‐cyclopenta [2,1‐b;3,4‐b′] dithiophene)‐alt‐4,7(2,1,3‐benzothiadiazole)] (PCPDTBT) diodes is visualized using Raman spectroscopy, and thermal effects due to self‐heating are quantified by exploiting temperature‐dependent shifts in the polymer vibrational modes. The temperature increases due to self‐heating are quantified by correlating the Raman shifts observed in electrically biased diodes with temperature‐dependent Raman measurements. Temperature elevations up to 75 K are demonstrated in the PCPDTBT diodes at moderate power of about 2.6–3.3 W cm−2. Numerical modeling rationalizes the significant role of Joule and recombination heating on the diode current–voltage characteristics. This work demonstrates a facile approach for in situ monitoring of self‐heating in organic semiconductors for a range of applications, from fundamental transport studies to thermal management in devices.