Single-material photodetector rivals performance of complex competitors
Researchers have built a light-sensing chip from just one organic material that matches the sensitivity of conventional multi-component designs. The simpler approach could cut manufacturing costs and improve stability for cameras, sensors, and imaging systems across consumer electronics and industrial applications.
Originaltitel: Sensitive self-driven single-component organic photodetector based on vapor-deposited small molecules
<p>Typically, organic solar cells (OSCs) and photodetectors (OPDs) comprise an electron donating and accepting material to facilitate efficient charge carrier generation. This approach has proven successful in achieving high-performance devices but has several drawbacks for upscaling and stability. This study presents a fully vacuum-deposited single-component OPD, employing the neat oligothiophene derivative DCV2-5T in the photoactive layer. Free charge carriers are generated with an internal quantum efficiency of 20 % at zero bias. By optimizing the device structure, a very low dark current of 3.4 · 10−11A cm−2 at −0.1 V is achieved, comparable to the dark current of state-of-the-art bulk heterojunction OPDs. This optimization results in specific detectivities of 1· 1013Jones (based on noise measurements), accompanied by a fast photoresponse (f-3dB = 200 kHz) and a broad linear dynamic range (> 150 dB). Ultrafast transient absorption spectroscopy unveils that charge carriers are already formed at very short time scales (< 1 ps). The surprisingly efficient bulk charge generation mechanism is attributed to a strong electronic coupling of the molecular exciton and charge transfer states. This work demonstrates the very high performance of single-component OPDs and proves that this novel device design is a successful strategy for highly efficient, morphological stable and easily manufacturable devices.</p>