Cost-effective high-performance quantum dot photodetectors with dual polythiophene hole transporting layers

The strong aggregation of Poly(3-hexylthiophene) (P3HT) severely limits its use as the hole-transport material in emerging quantum dot photodetectors and photovoltaics. Herein, we propose a facile and cost-effective strategy to control the solution-state aggregation of hole transporting layers by designing a dual polythiophene blend based on P3HT and its alkylthio-substituted analogue named Poly(3-hexylthiothiophene) (P3HTT). In our photodetector device, we have used the dual polythiophene as the hole transport layer and achieved a specific detectivity (D*) on the order of 1012 Jones. In particular, by incorporating a small amount of P3HTT into the dual polythiophene mixture, we observed a remarkable 28% performance enhancement. This study provides a comprehensive analysis of the solution structure of the dual polythiophene blend, elucidates the evolution of the condensed matter structure, and ultimately presents a promising avenue for enhancing the performance of low-cost quantum dot photodetectors.