摘要
全无机无铅双钙钛矿材料(Cs2AgBiBr6)具有载流子寿命长、稳定性高和禁带宽度适中等优点,近年来在光电探测器的应用研究上受到广泛关注.本文通过将水热法生长的TiO2纳米柱阵列嵌入到Cs2AgBiBr6层中形成紧密的核壳结构,增大两者的物理接触面积,提高光电探测器电子注入与电荷分离的效率.此外,TiO2纳米柱阵列还可以有效减小光在器件表面的反射损耗,增强Cs2AgBiBr6薄膜的光捕获能力.实验结果表明,基于TiO2纳米柱的多波段响应Cs2AgBiBr6双钙钛矿光电探测器在365 nm及405 nm多个波长均能激发高光响应且有良好稳定性和重复性,所得平均开关比分别为522和2090,以0.056 W/cm2固定光强激发,响应度分别为0.019 A/W和0.057 A/W,比探测率分别为1.9×1010 Jones和5.6×1010 Jones.相比于传统TiO2薄膜型Cs2AgBiBr6光电探测器,平均开关比分别提升65倍和110倍,响应度分别提升35％和256％,比探测率分别提升6.9倍和25倍.上述结果表明,基于TiO2纳米柱的多波段响应Cs2AgBiBr6双钙钛矿光电探测器可为提高光电器件的效率提供参考方案.
Abstract
Photodetectors are widely used in the fields of environmental monitoring,medical analysis,security surveillance,optical communication and biosensing due to their high responsiveness,fast response time,low power consumption,good stability and low processing cost.Fully inorganic lead-free perovskite material(Cs2AgBiBr6)has received a lot of attention in recent years in the research of photodetector applications due to its advantages of long carrier lifetime,high stability,moderate forbidden bandwidth,and environmental friendliness.For perovskite photodetectors,the semiconductor nanopillar array structure can effectively reduce the reflection loss of light from the surface to improve the absorption of incident light in the device and inhibit the exciton complexes in the device,and the good energy level matching between TiO2 and Cs2AgBiBr6 can effectively promote the transport and extraction of carriers in the device.However,there are few reports on the use of TiO2 nanopillar arrays as a transport layer to improve the performance of Cs2AgBiBr6 photodetectors.In this work,high-quality Cs2AgBiBr6 thin films with large grain size,no visible pinholes,and good uniform coverage are successfully prepared by a low-pressure-assisted spin-coating method under ambient conditions.Hydrothermally grown TiO2 nanopillar arrays are embedded into the Cs2AgBiBr6 layer to form a close core-shell structure,increasing the physical contact area between the two to ensure more effective electron injection and charge separation,and to improve the carrier transport efficiency in the device.Multi-band responsive Cs2AgBiBr6 double perovskite photodetectors based on TiO2 nanopillars are excited at multiple wavelengths of 365 nm and 405 nm with high light response and good stability and reproducibility,resulting in average switching ratios of 522 and 2090,respectively.When the light source is excited at 365 nm and 405 nm with a light intensity of 0.056 W/cm2,the responsivity is 0.019 A/W and 0.057 A/W,respectively,and the specific detectivity is 1.9 × 1010 Jones and 5.6 × 1010 Jones,respectively.Comparing with the Cs2AgBiBr6 perovskite photodetector based on a planar TiO2 electron transport layer,the average switching ratios are improved by a factor of 65 and 110,the responsivities are improved by 35％and 256％,and the specific detectivity are improved by a factor of 6.9 and 25,respectively.In this work,the photoelectric performance of Cs2AgBiBr6 photodetector is improved by using TiO2 nanopillars as an electron transport layer.It provides a reference solution for developing high-performance Cs2AgBiBr6 perovskite photodetectors in future.
基金项目
广西自然科学基金(桂科AD23026253)
国家自然科学基金(52262022)
国家自然科学基金(62205080)
广西精密导航技术与应用重点实验室项目(DH202202)
广西精密导航技术与应用重点实验室项目(DH202302)
广西类脑计算与智能芯片重点实验室开放基金(BCIC-23-K6)
万方数据