Unveiling InTe for flexible thermoelectric applications with enhanced performance via Bi/Se co-doping and MnO₂ integration

Conventional thermoelectric materials are limited by rigidity, high synthesis costs, and poor compatibility with flexible devices. Despite progress, the development of novel, low-cost, and scalable materials for flexible thermoelectrics remains limited. The novelty of this work lies in introducing InTe as a printable thermoelectric material and demonstrating the first screen-printed flexible thermoelectric generators (FTEGs) based on InTe. Pristine and Bi/Se co-doped InTe were synthesised via solid-state reaction and fabricated through a cost-effective, scalable screen-printing method. Co-doping effectively tuned the crystallinity, carrier concentration, mobility, and band structure. Among the co-doped samples, In0.94Bi0.06Te0.97Se0.03 achieved a Seebeck coefficient of ~ 1320 µV/K and showed a maximum power output of ~ 29.45 nW at a temperature gradient of 100 K. The other novelty of this work is the incorporation of MnO₂ to form a printed p–n heterojunction, which improves the conductive pathway, leading to a peak power output of 48.41 nW, approximately 1.64 times higher than that of the In0.94Bi0.06Te0.97Se0.03 sample. The FTEGs exhibited approximately 2% resistance variation after 500 bending cycles and at various angles, confirming excellent mechanical durability. This work establishes InTe as a promising printable thermoelectric material and highlights co-doping and MnO2 incorporation as powerful strategies for flexible energy harvesting.