A novel approach for designing efficient broadband photodetectors expanding from deep ultraviolet to near infrared

Broadband photodetection(PD)covering the deep ultraviolet to near-infrared(200–1000 nm)range is significant and desirable for various optoelectronic designs.Herein,we employ ultraviolet(UV)luminescent concentrators(LC),iodinebased perovskite quantum dots(PQDs),and organic bulk heterojunction(BHJ)as the UV,visible,and near-infrared(NIR)photosensitive layers,respectively,to construct a broadband heterojunction PD.Firstly,experimental and theoretical results reveal that optoelectronic properties and stability of CsPbI3 PQDs are significantly improved through Er3+doping,owing to the reduced defect density,improved charge mobility,increased formation energy,tolerance factor,etc.The narrow bandgap of CsPbI3:Er3+PQDs serves as a visible photosensitive layer of PD.Secondly,considering the matchable energy bandgap,the BHJ(BTP-4Cl:PBDB-TF)is selected as to NIR absorption layer to fabricate the hybrid structure with CsPbI3:Er3+PQDs.Thirdly,UV LC converts the UV light(200–400 nm)to visible light(400–700 nm),which is further absorbed by CsPbI3:Er3+PQDs.In contrast with other perovskites PDs and commercial Si PDs,our PD presents a relatively wide response range and high detectivity especially in UV and NIR regions(two orders of magnitude increase that of commercial Si PDs).Furthermore,the PD also demonstrates significantly enhanced air-and UV-stability,and the photocurrent of the device maintains 81.5%of the original one after 5000 cycles.This work highlights a new attempt for designing broadband PDs,which has application potential in optoelectronic devices.