Generally, photocurrent achieves saturation easily under high light intensity and/or high current density by exciton/carrier quenching; to the best of authors knowledge super-linear photoresponse has not been observed experimentally in all types of photodetectors before. This study has reported super-linear photoresponse organic phototransistors (OPTs) based on bulk heterojunction (BHJ) with PM6 as the donor and Y6 as the non-fullerene acceptor. The super-linear photoresponse has satisfied that the photocurrent is proportional to the 1.37 power of light intensity (linearity index ∂ = 1.37), in which gain achieves 280% (external quantum efficiency, EQE greater than 1) and detectivity (D_shot^*) achieves 1.88 × 10¹³ Jones at Vg of 5 V. The quick minority carrier release of non-fullerene acceptor can help reduce the threshold voltage drift and match the transconductance, improving the possibility of obtaining super-linear response regions. The graded distribution of donor/acceptor is more likely to reduce carrier quenching under high light intensity during the extension of Debye screening layer for effective super-linear response. By modulating the gate voltage, the linearity index can be adjusted from 0.5 to 2.33, where the super-linear photoresponse can automatically enlarge the contrast of the image. It has an excellent application prospect in intelligent contrast control in real time image recognition.

中文翻译：

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通过具有分级有源层的有机光电晶体管实现智能对比度控制的可调节超线性光响应

通常，在高光强和/或高电流密度下，通过激子/载流子猝灭，光电流很容易达到饱和；据作者所知，之前尚未在所有类型的光电探测器中通过实验观察到超线性光响应。本研究报道了基于体异质结（BHJ）的超线性光响应有机光电晶体管（OPT），PM6作为供体，Y6作为非富勒烯受体。超线性光响应满足光电流与光强度的1.37次方成正比（线性指数∂  =1.37），增益达到280%（外量子效率，EQE大于1）和探测率（D _shot ^*）在Vg为5 V时达到1.88×10 ¹³ Jones。非富勒烯受体的少数载流子快速释放有助于降低阈值电压漂移并匹配跨导，提高获得超线性响应区的可能性。供体/受体的分级分布更有可能减少德拜屏蔽层延伸过程中高光强度下的载流子猝灭，以实现有效的超线性响应。通过调制栅极电压，线性指数可在0.5至2.33之间调整，其中超线性光响应可以自动放大图像的对比度。在实时图像识别中的智能对比度控制方面具有良好的应用前景。