Abstract The development of lead‐free perovskites for optoelectronic applications remains a crucial challenge, particularly in achieving high performance at low operating voltages. Here, a 0D bismuth hybrid perovskite containing 2‐(2‐thienyl)pyridinium (TEP) as the organic cation, (2TEP) 4 Bi 2 I 10 ( TTBI ) is reported, that exhibits excellent photodetection capabilities and interesting thermochromic behavior. Single crystal X‐ray diffraction reveals a structure featuring isolated Bi 2 I 10 4 − dimeric units with short I···I contacts (3.87 Å), promoting enhanced electronic coupling. Density functional theory calculations confirm a direct bandgap of 1.79 eV, while flash‐photolysis time‐resolved microwave conductivity measurements demonstrate a remarkably long charge carrier lifetime of 7.3 µs. Notably, photodetector devices based on TTBI achieve impressive performance metrics at an ultra‐low bias voltage of 0.01 V, including a responsivity of 86 mA W −1 , a detectivity of 3.9 × 10 1 2 Jones, an on/off ratio of 10 4 , and an ultralow dark current of 1 pA. The material also exhibits reversible thermochromic behavior with bandgap modulation from 2.09 to 2.03 eV between 303 and 403 K, driven by thermal expansion and electron‐phonon coupling, enabling dual‐mode optical and thermal sensing. These findings, combined with excellent ambient stability, demonstrate the potential of TTBI as a versatile, environmentally friendly material for next‐generation optoelectronic applications.
Kizhakkumparaban et al. (Mon,) studied this question.