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Interface engineering of p-n heterojunction for kesterite photovoltaics: A progress review

“…Several groups reported that HT at around 200°C~300°C could enable moderate interdiffusion of Cd and Zn, which could form a thin layer of Cu 2 Cd x Zn 1-x SnS 4 in the CZTS surface as well as an ultrathin Zn 1-x Cd x S layer in between CZTS and CdS [47] (Copyright 2018, American Chemical Society). [1,76,77]. Consequently, thanks to such intermediate layers, a spike-like CBO band alignment between CZTS and CdS can be obtained (Fig.…”

“…Annealing a CZTSSe/CdS sample in air or a N 2 /Ar atmosphere is a simple method to enhance the quality of the interface [50,[74][75][76][77][78]. The improved heterojunction interface is attributed to two aspects: the order-disorder transition in the bulk [79][80][81] and the interdiffusion within the interfacial region [1,76,77].…”

“…Annealing a CZTSSe/CdS sample in air or a N 2 /Ar atmosphere is a simple method to enhance the quality of the interface [50,[74][75][76][77][78]. The improved heterojunction interface is attributed to two aspects: the order-disorder transition in the bulk [79][80][81] and the interdiffusion within the interfacial region [1,76,77]. The change in the order-disorder degree is identified by the studies in lowtemperature annealing (200°C~260°C) of the absorber, in which the detrimental defect with high formation energy could be alleviated but not for defect clusters with low formation energy [79][80][81].…”

Kesterite Solar Cells: Insights into Current Strategies and Challenges

“…Another widely adopted additional heat treatment strategy is the heterojunction/device annealing, i.e., heat treatment is applied after the deposition of the buffer layer/the completion of the device. [37,39,[77][78][79] Besides the advantages of improving absorber quality as discussed above, the heterojunction heat treatment Elemental mapping for CZTSSe thin film after annealing in the air, SnO x can be found within grain boundaries. Reproduced with permission.…”

“…[33][34][35] HJT induced interface element interdiffusion is beneficial to modify the conduction band alignment and thus reduce nonradiative recombination at the junction interface. [37,39,65,66,[77][78][79] For the pure sulfide or sulfide-rich kesterite, the conduction band offsets (CBO) of the heterojunction (kesterite/CdS) interface are cliff-like, aggravating nonradiative recombinations and is detrimental to the V oc and efficiency. [35] There are generally two ways to re-establish a favorable band alignment: i) applying alternative buffer materials with suitable conduction band energy such as Zn 1−x Cd x S, In 2 S 3 , and Zn 1−x Sn x O y ; [80][81][82][83] ii) using HJT induced elemental interdiffusion to construct a continuous conduction band alignment.…”