Internal field tailoring enables low noise high speed colloidal quantum dot photodetectors beyond 1500 nm

Colloidal quantum dots are attractive for short-wave infrared photodetectors owing to their solution processability and tunable bandgaps. However, excessive dark current remains an issue for low bandgap absorbers, where generation-recombination and tunneling currents become prominent. Diode architectures for photocarrier extraction rely on strong internal electric fields, which can amplify these leakage pathways. Here, we introduce a field-tailoring strategy to reshape the internal field distribution and suppress leakage currents. Using an indium arsenide absorber and a wide-bandgap p-type indium arsenide hole transport layer, we modulate the doping density via carbazole-based phosphonic acid ligands, enabling tuning of the internal field and band alignment. The device exhibits a dark current of 9.7 × 10⁻⁴ mA cm⁻² at -0.2 V, with a response time of 24 ns and a detectivity of 5 × 10¹¹ Jones at 1500 nm. The approach is extended to inverted architecture, demonstrating low-noise, high-speed photodetection beyond 1500 nm.