Organic narrowband near-infrared photodetectors based on intermolecular charge-transfer absorption

Abstract

Blending organic electron donors and acceptors yields intermolecular charge-transfer states with additional optical transitions below their optical gaps. In organic photovoltaic devices, such states play a crucial role and limit the operating voltage. Due to its extremely weak nature, direct intermolecular charge-transfer absorption often remains undetected and unused for photocurrent generation. Here, we use an optical microcavity to increase the typically negligible external quantum efficiency in the spectral region of charge-transfer absorption by more than 40 times, yielding values over 20%. We demonstrate narrowband detection with spectral widths down to 36 nm and resonance wavelengths between 810 and 1,550 nm, far below the optical gap of both donor and acceptor. The broad spectral tunability via a simple variation of the cavity thickness makes this innovative, flexible and potentially visibly transparent device principle highly suitable for integrated low-cost spectroscopic near-infrared photodetection.

Dimensionally Engineered Perovskite Heterostructure for Photovoltaic and Optoelectronic Applications

“…Band bending of a typical 2D|3D heterojunction and illustration of the EL mechanism. [41,42] The 2D has a single-crystalline-like phase and its bandgap is larger than that of the 3D. The discontinuity at the interface, i.e., valence band cusp appears.…”

Color‐Selective Printed Organic Photodiodes for Filterless Multichannel Visible Light Communication

“…As such, these devices have relied on device engineering approaches to limit their spectral responsivity range. Recently, solution‐processed wavelength selective OPDs have been realized by means of: i) optical filtering,5,22 ii) charge collection narrowing,23–25 and iii) cavity enhanced absorption 26–28. All of these techniques have demonstrated wavelength selective responsivity and enabled successful application in color reconstruction or IR‐spectroscopy.…”

Efficiency and spectral performance of narrowband organic and perovskite photodetectors: a cross-sectional review

“…Within the realm of internally filtered devices, the highest EQE of IntF-1 devices is at 13.6% [73]; IOEF|PCL generally perform below 30% [48,67,68,73,84,114,135] (with the exception of the work of Higashi et al which reaches 51% with an optimised architecture) [69]; CCN works typically give EQEs in the 1%-20% range [33,34,85,86,98] (the work of Arca et al reaching an EQE of 47%, is an important exception) [73]. The EQEs of most microcavity-based photodetectors are less or much less than 25% [42,65,[136][137][138][139] (the only exception being found in the work of Tang et al [42] who achieved EQEs up to 50% through detailed modelling and design). This is reflective of the fact that internally filtered and microcavity-based strategies are typically prone to greater photoconversion losses.…”